Tag Archives: Top-Grade Ammo

RELOADERS CORNER: Barrel Throat Erosion

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How long does a barrel last? About 5 seconds. KEEP READING

throat erosion
Well, it’s hotter than this, but it’s flame cutting over time and distance, and hotter for longer is the issue.

Glen Zediker

As is by now common enough in this column I write, ideas for topics very often come from questions that are emailed to me. As always, I figure that if someone has a question they want answered, then others might also like to know the answer. This question was about barrel life and, specifically, this fellow had been reading some materials on the interweb posted by some misinformed folks on the topic of bullet bearing area and its influence on barrel life: “Is it true that using 110 gr. vs. a 150 gr. .308 bullet will extend barrel life because of its reduced bore contact?”

NO. Not because of that.

However! The answer is also YES, but here’s why…

Wear in a barrel is virtually all due to throat erosion. The throat is the area in a barrel that extends from the case neck area in the chamber to maybe 4 inches farther forward. Erosion is the result of flame-cutting, which is hot gas from propellant consumption eating into the surface of the barrel steel. Same as a torch. There is very little wear caused from passage of the bullet through the bore, from the “sides” of the bullet, from friction or abrasion. The eroding flame cutting is at or near the base of the bullet.

When the propellant is consumed and creates the flame, the burn is most intense closer to the cartridge case neck. There are a few influences respecting more or less effect from this flame cutting. Primarily, it’s bullet weight. Time is now the main factor in the effect of the flame cutting. Slower acceleration means a longer time for the more intense flame to do its damage.

The slower the bullet starts, and the slower it moves, the more flame cuts in a smaller area for a longer time.

Bullet bearing area, therefore, has an influence on erosion, but that’s because it relates to acceleration — greater area, more drag, slower to move.

The amount of propellant, and the propellant nature, do also influence rate of erosion. Some assume that since there’s more propellant behind a lighter bullet that would create more erosion, and that’s true, but that is also not as great a factor as bullet weight. Other things equal, clearly, more propellant is going to cut steel more than less propellant. A “lighter” load will have a decidedly good effect on barrel life.

throat erosion
It’s heavier bullets that have the most influence on shortening barrel life.

Heavier bullets, without a doubt, are a greater influence than any other single factor. “We” (NRA High Power Rifle shooters) always supposed that it was the number of rapid-fire strings we ran that ate up barrels the most, but that was until we started using heavier bullets and found out in short order that our barrels weren’t lasting as long. That was moving from a 70gr. to an 80gr. bullet.

The “nature” of propellant is a loose reference to the individual flame temperatures associated with different ones. There have been some claims of greater barrel life from various propellants, but, generally, a double-base will produce higher flame temperature.

Even barrel twist rate plays a role, and, again, it’s related to resistance to movement — slower start in acceleration. Same goes for coated bullets: they have less resistance and move farther sooner, reducing the flame effect just a little. And, folks, it’s always “just a little.” It adds up though.

There are bullet design factors that influence erosion. A steady diet of flat-base bullets will extend barrel life. There’s been a belief for years and years that boat-tail bullets increase the rate of erosion because of the way the angled area deflects-directs the flame. And that is true! However, it’s not a reason not to use boat-tails, just a statement. We use boat-tails because they fly better on down the pike, and, ultimately that’s a welcome trade for a few less rounds. An odd and uncommon, but available, design, the “rebated boat-tail” sort of splits the difference and will, indeed, shoot better longer (they also tend to shoot better after a barrel throat is near the end of its life).

The effects or influences of barrel throat erosion are numerous, but the one that hurts accuracy the most is the steel surface damage. It gets rough, and that abrades the bullet jacket. The throat area also gets longer, and that’s why it’s referred to as “pushing” the throat.

The roughness can’t much be done about. There are abrasive treatments out there and I’ve had good luck with them. Abrasive coated bullets run through after each few hundred rounds can help to smooth the roughness, but then these also contribute their share to accelerated wear. I guess then it’s not so much a long life issue, but a quality of life issue. I do use these on my competition rifles.

lnl gage
Use the Hornady LNL O.A.L. gage to record and then track barrel throat wear. This isn’t technically a “throat erosion gage,” which do exist, but I’ve found it an easy and reliable way to keep up with an advancing throat. As the seating depth gets longer, it’s indicating how far the throat is advancing. Get one HERE 

Keeping in mind that the throat lengthens as erosion continues, using something like the Hornady LNL tool shown often in these pages can let bullet seating depth that touches the lands serve as a pretty good gage to determine the progress of erosion. On my race guns, I’ll pull the barrel when it’s +0.150 greater than it was new. Some say that’s excessively soon, and a commonly given figure from others in my circle is +0.250. One reason I pull sooner is that I notice a fall-off in accuracy sooner than that since I’m bound by a box magazine length for my overall cartridge length for magazine-fed rounds with shorter bullets, and I’m already starting with a fairly long throat (“Wylde” chamber cut). And another is because gas port erosion is having some effect on the bullet also by that number of rounds. Which now leads into the “big” question.

So, then, how long does a barrel last? Get out a calculator and multiply how many rounds you get before pulling a barrel by how long each bullet is in the barrel and barrels don’t really last very long at all! At full burn, maybe 4-6 seconds, some less, or a little more.

Another misgiven “fact” I see running rampant is associated with comparing stainless steel to chromemoly steel barrels for longevity. Stainless steel barrels will, yes, shoot their best for more rounds, but, chromemoly will shoot better for an overall longer time. Lemmeesplain: the difference is in the nature of the flame cutting effect on these two steels. Stainless tends to form cracks, looking like a dried up lakebed, while chromemoly tends to just get rough, like sandpaper. The cracks provide a little smoother surface for the bullet to run on (until they turn into something tantamount to a cheese grater). The thing is that when stainless stops shooting well it stops just like that. So, stainless will go another 10 to 15 percent more x-ring rounds, but chromemoly is liable to stay in the 10-ring at least that much longer than stainless steel.

throat erosion
Stainless steel barrels keep their “gilt-edge” accuracy for about 15% more rounds, but hit the wall head-on and in a big way when they reach their limit. Chromemoly steel tends to open up groups sooner, but also maintains “decent” accuracy for a longer time, by my experience — the groups open more slowly.

Do barrel coatings have an effect? Some. A little. I’ve yet to see one that made a significant difference, or at least commensurate with its extra expense. Chrome-lined barrels do, yes, tend to last longer (harder surface), but they also tend not to shoot as well, ever. Steel hardness factors, but most match barrels are made from pretty much the same stuff.

The preceding is a specially-adapted excerpt from Glen’s book Top-Grade Ammo. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

RELOADERS CORNER: Making Space

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Some reloading ops don’t have to be done in a full-blown shop. Here are a few ideas when space, and comfort, are both at a premium. READ MORE

home reloading
There are stand-alone and then set-aside mounting solutions for folks who don’t have shop space. This is from Lee and available here at Midsouth.

Glen Zediker

I recently, at his request, took on the task of teaching one son to reload for his AR15. It was in the middle of the winter and my shop/studio area was pretty much closed down for the season. But he persisted, and it was also just the sort of thing I needed to shift gears and give myself a test of what I truly do know that I set out to share with you all each edition. I say that sort of humorously, but not really! Getting back to the basics, starting from the start, is a great idea. I recollect from experiences in what amounted to another life for me (I used to be a PGA Member), the great golf champion Jack Nicklaus would return to his original teacher, Jack Grout, at the start of each PGA Tour season and say: “I’m Jack Nicklaus. I’ve been thinking about taking up golf. Can you show me how to hold the club?”

So the immediate challenge for me was to make this learning experience worthwhile and also comfortable! And easy given the busy schedules we both have.

Many of us have well thought out and lavishly equipped reloading work spaces, and, others, not so much. All during the many many years I’ve been reloading, I’ve lived in apartments, moved to new locations, and, either way, didn’t always have access to the well-lit and sturdily-constructed “loading bench.”

I’ve made do, and, looking back, I don’t think I ever missed a point as a result.

Tricks and Tips
C-clamps are wonderful allies! Mounting many tools doesn’t require direct bench-top fastening. For years, even with a full-scale shop to stretch out in, I have been a fan of mounting tools on “platforms” and then clamping that to the bench when needed. I have a penchant for efficiency in loading and a big part of satisfying that is being able to relocate tools. In other words, I don’t want to have a trimmer, priming tool, and so on and on, all mounted in a (long) row along my benchtop. I want to be able to locate them where I want them, when I need them.

home reloading
A little creativity can mount most tools for easy location-relocation. Drill straight! That matters.
home reloading
Here’s a Forster trimmer mounted to that wood piece that can pretty much clamp anywhere.

Get to the hardware store and invest in some wood pieces, fastener-fixtures, and hex-head-screws. Take a priming tool, for instance, and mount it to the wood and then clamp that to the benchtop (or any suitable surface, anywhere) and commence to using it. Simple!

home reloading
This is an easy way to mount a quickly removable tool, like this small Lee press.

I’ve also had good success locating the tool mount spots I prefer for various appliances on my benchtop and then using the hex-head screws to attach the tools via installed threaded fastener receptacles when I want to use them.

home reloading
Built-in clamps are where it’s at. I’m a big fan of Harrell’s Precision tools and the omnipresent clamp is one small reason why.

I’ve even taken to doing that in mounting big tools. The bench where I load ammo is also the same bench where I build guns, or they share common area. After getting tired of bolting and unbolting vises and presses, I mounted each to a 2X12 piece of wood and affix either to the benchtop using a couple of honking c-clamps. As long as there’s enough area to get a good clamp down and enough surface area to sit the bench, I cannot tell the difference.

Now, when it comes to some higher weight and higher leverage tools, like presses, some of what you can get away with, in a way of looking at it, has a lot to do with how sturdy the base platform needs to be. Sizing .223 Rem.? Not much stress. Bigger cases, more stubborn ops, might need more substantial grounding.

For us, a combination of c-clamps and factory-mounted clamps on some of our meters and presses meant we could set up alongside each other at, believe it or not, our kitchen table and load in comfort, and easy access to a refrigerator!

home reloading
An assortment of fasteners: t-bolts and barrel screws from a hardware store, along with a c-clamp.

There are also some handy ready-made bases for loading available HERE at Midsouth.

Point is, if you don’t have access to a conventional bench, work area, or you want to prime cases while you’re watching television with your friends or family, there’s a solution. It just takes a little creativity.

Just pay attention to the loading!

home reloading
Here’s son Charlie ready to learn how to set up a sizing die… In the comfort of our kitchen, in the middle of the winter. Ammo loaded here shoots just as well as that done in the shop.

The preceding is a specially-adapted excerpt from Glen’s book Top-Grade Ammo. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

RELOADERS CORNER: Standard Deviation

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Before getting into improving bullet velocity Standard Deviation, it’s first necessary to understand what it is, and what it isn’t. KEEP READING

chronograph screen

Glen Zediker

I got started on this topic last time, and kind of came in through the side door. Quick backstory: the topic was how to start on solving unsuitably high shot-to-shot velocity inconsistencies. This time we’ll start at the other end of this, and that is taking steps to improve already suitable velocity deviation figures.

Clearly, the first step in getting involved in velocity studies is getting the velocities to study. Of course, that means you need a chronograph. Midsouth Shooters has a selection and there’s a direct link in this article.

Virtually all chronographs are going to be accurate. A well-known manufacturer of shooting-industry electronics once told me that unless a chronograph displays a reading that’s just crazy unrealistic, you can rely on the number. The reason is that the current state of circuitry is pretty well understood and heavily shared. Pay attention, though, to setting up the device according to suggestions in the instructions that will accompany the new chronograph. The more recent Doppler-radar-based units are not technically chronographs, but they function as such. The advantages to those are many! More in another article soon. For now, for here, what matters is getting some numbers.

labradar
Latest and greatest, in my mind, advancement in data collection is doppler radar based units, like this from LabRadar. Easy to use, and not finicky about sunlight and setup.

Point of all that was this: You don’t have to spend up for the best to get a good chronograph. One of the price-point differences in chronographs is how much it will help work with the data it gathers. Most of us any more don’t have to do hands-on calculations. Me? All I want is a number. However, there are a good many that will record, calculate, and print.

magnetospeed
Barrel-mounted electro-magnetic chronographs like this one from MagnetoSpeed make it easy. I like being able to read speeds without all the setup, and not having to rely on a benchrest-type restriction. It stays on the rifle so can easily be used in the field. There are rail mounts available also.

Terms and Twists
Speaking of calculations, the most known and probably most used expressed calculation of collected velocity figures is Standard Deviation. SD suggests or reflects the anticipated consistency of bullet velocities (calculated from some number of recorded velocities). “Standard” reflects on a sort of an average of the rounds tested. I know saying “sort of” disturbs folks like my math-major son so here’s more: SD is the square root of the mean of the squares of the deviations.

Standard Deviation calculations did not originate from ballistic research. It’s from statistical analysis and can be applied to a huge number of topics, like population behavior. SD calculation forms a bell curve, familiar to anyone who ever had to take a dreaded Statistics class. The steeper and narrower the apex of the bell, the narrower the fluctuations were. But there’s always a bell to a bell curve and the greatest deviations from desired standard are reflected in this portion of the plot. Depending on the number of shots that went into the SD calculation, these deviations may be more or less notable than the SD figure suggests.

Calculating SD
If you have no electronic gadgetry to help: add up all the recorded velocities and divide them by the number of records to get a “mean.” Then subtract that mean value from each single velocity recorded to get a “deviation” from the mean. Then square each of those. Squaring them eliminates any negative numbers that might result from cancelling out and returning a “0.” Add the squares together and find the mean of the squares by dividing again by the number of numbers — minus 1 (divide by n -1; that eliminates a bias toward a misleadingly small result). Then find the square root of that and that’s the Standard Deviation figure, which is “a” Standard Deviation, by the way, not the Standard Deviation.

bell curve
This is a bell curve such as results from plotting an SD calculation, and is given here only an example of how the distribution, the “odds,” graph out.

Knowing a load’s SD allows us to estimate-anticipate how likely it is for “outliers” to show up as we’re shooting one round after another. Based on the distribution based on the curve, if we have an SD of 12, for instance, then a little better than 2 out of 3 shots will be at or closer to the mean than 12 feet per second (fps). The other shots will deviate farther: about 9 out of 10 will be 19 fps, or less, from the mean. 21 out of 22 will be 24 fps closer to the mean. Those numbers represent about 1.00, 1.65, and 2.00 standard deviations.

Now. All that may have ranged from really boring to somewhat helpful, to, at the least, I hope informative.

Mastery of SD calculation and understanding doesn’t necessarily mean smaller groups. It gives a way to, mostly and above all else, tell us, one, the potential of the ammo to deliver consistent elevation impacts, and, two, reflects on both how well we’re doing our job in assembling the ammo and the suitability of our component combination.

I honestly pay zero attention to SD. I go on two other terms, two other numbers. One is “range,” which is the lowest and highest speeds recorded in a session. The one that really matters to me, though, is “extreme spread.” That, misleading on the front end, is defined as the difference between this shot and the next shot, and then that shot and the next shot, and so on. Why? Because that’s how I shoot tournament rounds! This one, then another, and then another. A low extreme spread means that the accuracy of my judgment of my wind call has some support.

Depending on the number of shots and more, SD can be misleading because it gets a little smaller with greater amounts of input. Extreme spread doesn’t. I have yet to calculate an SD that put its single figure greater than my extreme spread records.

Lemmeesplain: The shot-to-shot routine is to fire a round. It’s either centered or not. If it’s not centered, calculate the amount of correction to get the next one to center. Put that on the sight. Fire again. If I know that there’s no more than 10 fps between those rounds, that’s no enough to account for (technically it can’t be accounted for with a 1/4-MOA sight) then it’s all on me, and if it’s all on me I know that the input I got from the last shot, applied to the next shot, will be telling. Was I right or wrong? It can’t be the ammo, folks. Then I know better whether the correction is true and correct.

Some might be thinking “what’s the difference?” and it’s small, and so are scoring lines.

A load that calculates to a low SD is not automatically going to group small, just because it has a low SD. Champion Benchrest competitors have told me that their best groups don’t always come with a low-SD load. But that does not apply to shooting greater distance! A bullet’s time of flight and speed loss are both so relatively small at 100 yards that any reasonable variation in bullet velocities (even a 20 SD) isn’t going to open a group, not even the miniscule clusters it takes to be competitive in that sport. On downrange, though, it really starts to matter.

For an example from my notes: Sierra 190gr .308 MatchKing, in a .308 Win. Its 2600 fps muzzle velocity becomes 2450 at 100 yards and 1750 at 600 yards (I rounded these numbers).

If we’re working with a horrid 100 fps muzzle velocity change, that means one bullet could lauch at 2550 and the next might hit 2650, in the extreme. The first drifts about 28 inches (let’s make it a constant full-value 10-mph wind again to keep it simple) and the faster one slides 26 inches. That’s not a huge deal. However! Drop — that is THE factor, and here’s where inconsistent velocities really hurt. With that 190, drop amount differences over a 100 fps range are about 3 times as great as drift amounts. This bullet at 2600 muzzle velocity hits 5-6 inches higher or lower for each 50 fps muzzle velocity difference. That is going to cost on target. And it gets way (way) worse at 1000 yards. Velocity-caused errors compound on top of “normal” group dispersion (which would be group size given perfect velocity consistency).

This 100 fps example is completely extreme, but half of that, or even a quarter of that, still blows up a score, or creates a miss on an important target.

That all led to this: What is a tolerable SD?

I say 12. There has been much (a huge amount) of calculation that led to that answer. But that’s what I say is the SD that “doesn’t matter” to accuracy. It’s more than I’ll accept for a tournament load, but for those I’m looking for an extreme spread less than 10 fps (the range might be higher, but now we’re just talking terms). More later…

Check out chronographs HERE

This article is adapted from Glen’s book, Handloading For Competition, available at Midsouth HERE. For more information on that and other books by Glen, visit ZedikerPublishing.com

RELOADERS CORNER: Velocity Consistency, Part One

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Shot-to-shot muzzle velocity consistency is almost always a high-ranking goal for the handloader. But what about when it’s just awful? READ MORE

chronograph display

Glen Zediker

Last edition the topic was a wide-scope look at propellants, and the underlying point was how to get started, how to choose one. There’s not a perfect answer to that, or not one I can warrant as absolutely decisive.

Propellant choice often comes down to experience (good and bad), and that’s one reason that many of us, and me most definitely, tend to stick with a few, and those also are the first we’ll try when starting up with a new project. It’s also one reason we might be hesitant to try a propellant again if it didn’t work well the last time. I have those hesitations.

There are also criteria that we’d all like to have met, and, as also said last time, sometimes those have to be ranked or weighted. We may not find the maximum velocity with the smallest group size with one propellant, and, for me, group size gets the most weight. That’s why I said that the best choice is often the one with the fewest compromises, and that’s assuming there’s likely to be some compromise, somewhere. And that’s a fair and wise assumption.

One criteria that I and others have pretty high on our lists is velocity consistency. One measure of a “good load” is low variations in measured muzzle velocities. This, without a doubt, is of more importance the more distant the target.

The propellant that tested showing the lowest shot-to-shot velocity deviation does not necessarily mean that load combination is going to be the most accurate. One reason it’s important might not only to do with on-target accuracy as it does with providing clues about either the handloading protocols we’re following or the suitability of the component combination we’re using.

This article will focus more on that last — suitability of the component combination — and more to follow later will be dedicated to the performance component of consistent velocities.

I got a letter just before doing this article asking about reasons for seeing high velocity deviations. This fellow, a loyal reader of my books, was using the same component combinations and tooling advice I take myself and also publish, and not getting good results. As a matter of fact, his results were horrid. He was seeing deviations, shot-to-shot, in the vicinity of 100 feet per second (fps), plus. That’s huge.

After much time spent testing all this to collect enough notebook entries to think I have some handle on it, a half grain (0.50 gr.) of propellant in most small- to medium-capacity cases (say from .223 Rem. to .308 Win.) is worth about 40 fps. Given that, 100 fps difference is not likely to come from a propellant charge level variance.

Another reader posted a comment-question last article here regarding how to know if aged components were still good, still performing as they should, and this is a place to start looking if we’re seeing radical inconsistencies.

Two questions at the same time, as I’ve said before, usually point me toward a topic.

Moisture is the enemy in propellant and primer storage. The “cool dry place” is hard to come by, around these parts anyhow. I’ve had propellant go bad after having been stored in resealed containers. So far, I haven’t had any lose its potency after many years of storage in the factory-sealed containers.

“Go bad” can mean at a couple of things, by the way. One is that the propellant ages to the point that it changes. If propellant “spoils” it smells bad! It will have an acrid aroma. Don’t use it. Another way it goes bad is pretty easy to tell: it clumps. That is too much moisture. Don’t use it. Put it out in the garden, it’s a great fertilizer — honest.

Primers? It’s hard to tell… Bad primers still appear good.

My letter-writer’s huge velocity deviations were solved by a change of primer, and, mostly, a box of fresh primers. I kind of knew that was the component-culprit because he was having the same results or effects from different propellants.

Primers should be stored in air-tight containers, which will be something other than the factory packaging. Primers are “sealed” but that’s a lightweight assurance. Touching them, for instance, won’t hurt them, contrary to rumors, but more prolonged exposure to excessive moisture can and will take a toll, and its effects are very likely to be as inconsistent as the performance of the compromised primers.

Another strong caution: Always remove, or never leave, however you prefer, propellant in a meter. After you’re done with the loading for the day, return it to its storage container and cap it back tightly. Same with primers. Any left over in the priming tube or tray should go back to safe storage. Clearly, this all has a lot to do with the environmental conditions of your loading-storage area.

Out of curiosity, I filled a case with some small-grained extruded propellant and left it sit out in my shop. It was clumped when I checked it next day (24 hours). I had to get a pipe cleaner (nearest handy tool) to get it all out of the case. I don’t store propellant or primers in my shop, and that’s the reason… Yes, we have some humidity in my part of the world.

Excluding those obvious issues, what makes some combinations produce higher or lower velocity consistencies takes some experimentation to improve (or give up on).

Sometimes (many times) this all seems more like art than science. It is science, of course, but it’s not tidy; it can’t always, or even often, be forecast.

I’ve seen the biggest effect from a primer brand change. I also, though, don’t swap primer brands around each time I do a load work up and the reason is that there are other attributes I need from a primer. Since I’m loading nearly always for a semi-auto, an AR15 specifically, I have to use a “tough” primer, and that also means one that will accept near-max pressure without incident.

Point is that if you’re running a rifle/ammo combination that isn’t limited by either propellant choice or primer choice, you might very well see some influential improvements by trying a different primer (after getting the propellant decided on). Do, always, reduce the charge at least a half grain before using a different primer brand — primer choices also decidedly influence velocity and pressure levels. Again, in my experience, more than you might imagine.

Next time, more about the performance component of consistent velocities, and a whopping lot more about how to improve that.

Check Midsouth storage solutions HERE

The preceding is a specially-adapted excerpt from Glen’s book Top-Grade Ammo. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

RELOADERS CORNER: Picking Propellants

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There are a whopping lot of propellants on the market. How do you choose one? Well, usually it’s more than one… READ WHY

PROPELLANT

Glen Zediker

All we ever really want is a propellant that provides high consistent velocity, small groups at distance, safe pressures over a wide range of temperatures, and burns cleanly, and, of course, it should meter perfectly. Dang. I know, right?

Ultimately, propellant choice often ends up as a compromise and it may well be that the smallest compromises identify the better propellants. Getting the most good from your choice, in other words, with the fewest liabilities.

There are two tiers of basics defining centerfire rifle propellant formulas. The granule form can be either spherical (round granules) or extruded (cylindrical granules). Next, the composition can be either single- or double-base. All propellants have nitrocellulose as the base; double-base stirs in some nitroglycerol to increase energy.

There’s been a good deal of effort expended and applied over the past several years to reduce the temperature sensitivity of propellant. Coatings come first to mind, and I use nothing but these “treated” propellants.

This attribute is very (very) important! It’s more important the more rounds you fire throughout a year. A competitive shooter’s score hinges on consistent ammunition performance. Test in Mississippi and then go to Ohio and expect there to be some change in zero, but a change in accuracy or a sudden excess of pressure and that’s a long trip back home. It’s common enough for temperatures to (relatively speaking) plummet on at least one day at the National Matches, so my 95-degree load has to function when it’s 50.

extruded propellant

Some are decidedly better than others in this. There are several propellants I’ve tried and will not use because I didn’t get reliable results when conditions changed. Some gave outstanding groups on target, on that day, at that hour, but went goofy the next month when it was +20 degrees. Heat and cold can influence pressure in a sensitive propellant.

Single-base extruded (“stick”) propellants are my first choice. A good example of one of those is Hodgdon 4895. These tend to be flexible in maintaining performance over a wider range of velocities, related to a wider range of charge weights. For instance, I’ll vary the charge weight of the same propellant for ammo for different yard lines. I’m reducing recoil or increasing velocity, depending on what matters more. Zero and velocity are different, but accuracy doesn’t change.

H4895
There are a few single-base extruded propellants that show impressive flexibility in load levels as well as in different round structures. This is one of the most flexible I’ve used, and I use a lot of it!

Spherical or “ball” propellants (these are double-base) are a good choice for high-volume production, and also tend to be a great choice for highest velocities at safe pressures. These meter with liquid precision. They, however, tend to be less flexible. That means they tend to work best at a set and fairly finite charge and don’t do as well at much less or more than that, and especially at much less than that. More in a minute.

spherical propellant
Spherical propellants tend to be volume sensitive. My experience has been they’ll perform best when the fill level is a good 90-percent. That means there’s a little smaller gap between one that’s good with, say, 50gr bullets and one that works well with 60s. It’s likely to be two propellant choices, not just one. Generally, spherical propellants do their best when loaded near-to-max.

Double-base extruded propellants (sometimes called “high-energy”) do, yes, produce higher velocities at equal pressures compared to single-base but also tend to be less flexible and exhibit performance changes along with temperature changes. Vihta-Vuori and Alliant are the best known for their formulations in these. Double-base usually burns at a hotter temperature (not faster or slower, just hotter) and can increase throat erosion rate. Some double-base spherical propellants claim to burn cooler. I’m not certain that this is a huge selling point, either way, for a serious shooter, but, there it is.

VV540
Double-base extruded propellants are mighty fuels, but, they tend GENERALLY to be more temperature sensitive and also burn hotter. Now. That’s not always true (I think NONE one of this is always true). With Viht. you can have a choice of double- or single-base in the same essential burning rate; N140 is single-base, N540 is double.

All propellants are ranked by burning rate. That’s easy. That’s just how quickly the powder will consume itself. All reloading data manuals I’ve seen list propellant data in order from faster to slower. For instance, if you’re looking at .223 Remington data and start off with tables for 40-grain bullets, you’ll see faster propellants to start the list than you will moving over to the suggestions for 75-grain bullets.

It’s tough to find a perfect propellant for a wide range of same-caliber bullet weights. Faster-burning propellants tend to do better with lighter bullets and slower-burning tends to get more from heavier bullets. That’s all about pressure and volume compatibility. Again, I have found that a single-base extruded propellant will work overall better over, say, a 20-plus-grain bullet weight range than a single choice in a spherical propellant.

scale pan with powder
Extruded propellants vary greatly in granule size, and, usually, the smaller the better. More precise metering. This is VV540, strong stuff, meters well. There are a few now that are very (very) small-grained (like Hodgdon Benchmark).

The idea, or at least as I’ll present my take on it, is that we want a fairly full case but not completely full. I don’t like running compressed loads (crunching a bullet down cannot be a good thing), and excessive air space is linked to inconsistent combustion. We ran tests upmteen years ago with M1As and found that out. Many details omitted, but here was the end: Settling the propellant back in the case prior to each shot absolutely reduced shot-to-shot velocity differences (the load was with a 4895, necessary for port pressure limits, and didn’t fully fill the case).

Generally, and that’s a word I’ll use a lot in this (and that’s because I know enough exceptions), spherical propellants have always performed best for me and those I share notes with when they’re running close to a max-level charge. More specifically, not much luck with reduced-level charges.

Too little spherical propellant, and I’m talking about a “light” load, can create quirky pressure issues. Workable loads are fenced into in a narrower range. This all has to do with the fill volume of propellant in the capped cartridge case, and, as suggested, that’s usually better more than less. That further means, also as suggested, there is less likely to be one spherical propellant choice that’s going to cover a wide range of bullet weights. That’s also a good reason there are so many available.

With some spherical propellants, going from a good performing load at, say 25 grains, and dropping to 23 can be too much reduction. One sign that the fill volume is insufficient is seeing a “fireball” at the muzzle. Unsettling to say the least.

Spherical propellants also seem to do their best with a “hot” primer. Imagine how many more individual coated pieces of propellant there are in a 25-grain load of spherical compared to a 25-grain charge of extruded, and it makes sense.

However! I sho don’t let that stop me from using them! I load a whopping lot of spherical for our daily range days. We’re not running a light load and we’re not running heavy bullet. We are, for what it’s worth, running H335.

So, still, how do you choose a propellant? Where do you start? I really wish I had a better answer than to only tell you what I use, or what I won’t use. There are a lot of good industry sources and one I’ve had experience with, including a recent phone session helping me sort out Benchmark, is Hodgdon. You can call and talk with someone, not just input data. Recommended.

When it’s time, though, to “get serious” and pack up for a tournament, I’m going to be packing a box full of rounds made with a single-base extruded propellant that meters well. As mentioned before in these pages, I have no choice in that, really. I’ll only run the same bullet jackets and same propellant through the same barrel on the same day. I need a propellant that works for anything between 70- and 90-grain bullets.

With time comes experience, and I know I sure tend to fall back on recollections of good experiences. I admittedly am not an eager tester of new (to me) propellants. I have some I fall back on, and those tend to be the first I try with a new combination. There are always going to be new propellants. That’s not a static industry. I may seem very much stuck in the past, but I no longer try every new propellant out there. I like to have some background with a propellant, meaning I’ve seen its results in different rifles and component combinations. Mostly, I ask one of those folks who tries every new propellant…

There is a lot of information on the internet. You’re on the internet now. However! There’s also not much if anything in the way of warranty. If you see the same propellant mentioned for the same application a lot of times, take that as a sign it might work well for you. Do not, however, short cut the very important step of working up toward a final charge. Take any loads you see and drop them a good half-grain, and make sure the other components you’re using are a close match for those in the published data.

One last: Speaking of temperature sensitivity: Watch out out there folks. It is easily possible for a round to detonate in a rifle chamber if it’s left long enough. Yes, it has to be really hot, but don’t take a risk. A rash of rapid-fire can create enough heat. Make sure you unload your rifle! Here’s an article you might find interesting.

CHECK OUT CHOICES AT MIDSOUTH
Hodgdon
Shooters World
Vihtavuori
Alliant

The preceding is a specially-adapted excerpt from Glen’s book Top-Grade Ammo. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

 

RELOADERS CORNER: Understanding Ballistic Coefficient

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Math and myth both get involved in bullet Ballistic Coefficient discussions. Keep reading to separate the two and learn exactly what BC is, and what it isn’t. MORE

bc

Glen Zediker

Years ago I explained in great detail to a fellow here all about ballistic coefficient and how it was calculated and how it could be used and how it can change and so on, and he stopped me: “So you mean it’ll hit furtherer on up the hill…” That’s it.

A “ballistic coefficient,” or “BC,” is a number assigned to a bullet that suggests its aerodynamic performance.

That’s a key word, “suggests.” The main suggestion is how well this bullet will fly compared to that bullet, and the one with the higher BC ought to fly better. Fly better means less drop and drift, and those, factually, are a product of the higher-number BC. My best all-inclusive definition what a higher BC does for us: less speed lost over distance. Regardless of the muzzle velocity or the distance, one bullet with a higher BC will lose relatively less velocity over the same distance.

bullet blueprint
Here’s a blueprint. All the information needed to calculate a BC is contained here. It doesn’t have to be a real bullet because a BC model is not a real bullet either. Design factors that influence BC are virtually every design factor: length, ogive, boat-tail, meplat, weight. These factors, in this instance, calculate to a G1 BC of 0.560. By the way, there’s about a 5 point BC increase for each added 1 grain of bullet weight.

BC is calculated based on a standard bullet model. There are 7 of those. Two are normally used to determine BC for conventional rifle bullets, like what the most of us reading this use. Ballisticians and designers know which model to apply to different bullet types. The common model is a “G1” (another is G7, which is becoming the popular standard for boat-tail bullets; G1 is based on a flat-base). The flight of this G1 bullet has been calculated at varying velocities and distances. It’s “all math” because a G1 does not in fact exist. BCs are derived by comparison.

g1
The older standard for most rifle bullets was the G1. The newer, and better, standard is the G7. However! BC is never chiseled into stone regardless of the model. It’s a way to compare bullets, and a place to start figuring yours out.

g1 and g7

The standard bullet of any form-factor has a BC of 1.000. An actual bullet that’s compared to the model at points downrange will either be flying faster or slower than the model. If it’s moving faster, its BC will be greater than 1.000. If it’s going slower, it will be less than 1.000. It’s a percentage of the standard or model bullet’s performance.

Now. That is also all that it is!

BC is not an infallible factual statement about precisely what a bullet will be doing when it’s loaded and fired at that target than moment with that rifle. Not nearly, not hardly.

To me, BC gives us a place to start estimating drop (elevation) and also clues to how much it will get moved by a wind. It’s a way to compare bullets.

BC changes! Day to day, place to place, hour to hour.

Some bullet makers publish a BC for a bullet based on actual testing (chronographs) but now it’s pretty much “just math.” That’s fine. Which — math or measure — provides the best information? Some believe that a measured, tested BC is more realistic and, therefore, more valuable. But, if the point is to compare bullets, calculated BCs is more reliably accurate.

We (NRA High Power Rifle shooters) have gone to difficult and frustrating lengths to collect data to calculate “real” BCs (chronographing at 500+ yards hain’t always easy). Measured BCs are quite often lower, and they are quite often higher. Reasons follow.

The accuracy of drift and drop tables clearly revolves around what the actual, at that moment, BC performance is from the bullet you’re shooting (compared to what it’s “supposed” to be).

Anything that can influence bullet flight influences the actual, demonstrated BC performance.

BC uniformity is important. Bullets that show uniform BC performance produce less elevation dispersion. A source for variation is the meplat (bullet tip). Hollowpoint match bullets are notorious for inconsistency in this area. There’s a tool, a “meplat uniformer,” that fixes it. That’s pretty much the point to the plastic points on bullets like Hornady’s A-Max line.

Atmospherics, which add up as a list of factors, have a huge influence on BC performance. Air density is probably the most powerful influence. Any conditions that allow for easier passage of a bullet through the air don’t detract as much from its stated BC as do any conditions that serve to disrupt its headway. BCs are based on sea-level so can easily show as a higher number at a higher elevation. I can tell you that bullets fired at The Whittington Center in New Mexico have a noticeably better BC than those shot at Port Clinton, Ohio.

Range reality is that the demonstrated BC changes from morning to afternoon and day to day and place to place. The calculated BC is not changing, of course, but the mistake is assuming that a BC is a finite measure of bullet performance.

Bullet stability is even a factor. For a stated BC to be shown on a shot, the bullet has to be “asleep.” If it’s not stable, it’s encountering disruptions that will slow it down. The rotational speed of a bullet in a test can influence BC. We’ve seen differences comparing different twist-rate barrels, and the faster twists often show a little lower tested BC.

Factors that don’t matter in BC? Caliber. I’ve been argued at often over this next, but it is perfectly and absolutely true: BCs work the same regardless of caliber or bullet weight. Two bullets that each have a 0.550 BC, for instance, behave the same. That’s helpful, and at one time was more helpful than it is now. When we had to use paper tables to get drift and drop data and there was a new bullet that didn’t yet have those tables done, all you had to do was find data for another bullet with the same BC, go to the same muzzle velocity, and that data was 100-percent accurate. A .308 and .224 that both have the same BC share the same table. Remember, it’s not “real,” it’s a mathematical model.

So if you take a load to the target one day and you’re putting on more elevation than the BC-based calculation says you should, the BC isn’t wrong. The day is just different.

Finally, does it matter (really) if a bullet BC is based on a G1 or G7 model? Debates continue. But, not really, and I say that because BC is still only a suggestion. G7 is a more closely matched model to what we’re usually shooting when we think of a “high-BC” bullet, but all the same factors day to day also influence its accuracy. Given access to the data, I definitely, though, go with G7 calculations to have a place to start from. My experience has been that there is less difference in varying conditions, but, again, it’s still (plenty) enough change that you cannot dial it in and win anything…

The preceding is a specially-adapted excerpt from Glen’s book Handloading For Competition. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

RELOADERS CORNER: 4 Bullet Seating Tips

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It’s the “last thing” that happens in handloading, and here’s a few ways to make it better. READ MORE

bullet seating

Glen Zediker

Last time the topic was bullet seating, but with a focus on safety — respecting the overall cartridge length that touches the lands or rifling in a barrel — and specifically making sure your bullet isn’t touching the lands (unless that’s what you want). This time here are a few ideas on how to improve the quality and consistency of bullet seating, and mostly from a tooling perspective.

A few things matter. The ultimate goodness is a round capped by a bullet that’s straight and undamaged, ready to get launched straight into the bore and then straight on to target center.

1. Die Design
I have long and often said that the single-most important tooling upgrade to improve the accuracy of handloaded ammunition is a better seating die. “Better” is better designed, and better designed, in my mind, is one that follows the “in-line” architecture.

LE wilson bullet seater
Here’s an LE Wilson die. There’s none more precise, but there are many faster to use! The sleeve-style seaters provide a close duplication in performance and results.

One of the first that comes to mind is the LE Wilson seater (there are others similar, but it’s the most well known). This seater style is the staple of Benchrest competitors. It’s not practicable for the most of us because it’s slow and a little tedious. How it works is that there is a seating stem that’s a very close fit to the die body. The die body and stem are concentric thanks to precision machining. The die body goes over the case, which has had a bullet placed in its neck, and the die holds the case in stable alignment. The stem is pushed down, seating the bullet. There’s zero “wiggle room.”

The difference in effect between that and a “standard” seating die, which has a stem threaded into a 7/8-14 press-mounted die body, is that the case isn’t free to move. In a conventional thread-in design, there’s a lot of room for movement in the case as it’s being run up into this type die. There’s slack in the case-shellholder fit, and slack in the fit of the case inside the die body. When the bullet that’s perched in the case mouth contacts the seating stem there’s a good chance it can get tilted askew. That then means there’s a good chance the bullet won’t be seated dead straight.

redding seating die
Here’s a Redding Competition Seating Die. The case is supported fully within a spring-loaded sleeve prior to accepting the bullet. Better!

Redding and Forster both make a press-mounted die that effectively duplicates the in-line Wilson concept. These both have a spring-loaded sleeve that tightly fits the case body. The idea is that the case fully enters this sleeve and is therefore fully supported against movement before the press handle stroke elevates the ram enough for the bullet to engage the seating stem. Much better!

2. Stem Check
Make sure that the tip of the bullet you’re using doesn’t contact the inside of the seating stem! This isn’t as common to see now as it once was. Longer, higher-BC type bullet profiles are prevalent enough that most manufacturers have increased the room inside the stem.

bad seating die stem
Not as common now as it used to be, but here’s what you don’t want! The bullet tip should not contact inside the seating stem.

Certainly, if the tip is bottoming out inside the stem, a few bad things can happen. One is that it’s easily free to tilt the bullet. Two is that the seating depth is then influenced by the tip-to-tip inconsistencies that do exist. Three is that the tip might get damaged in the process. This, by the way, is not nearly exclusively a concern to users of “spikey” bullets. I’ve been running into tip contact created by bullets with more blunt/rounded nosecones, like some of the lighter-weight .308 caliber bullets we’re using in .300 Blackout.

forster custom seating stem
If you’re a Forster user, they can supply a custom-dimensioned stem. I’ve been using these a while now and think it’s a great idea.

There’s more, though. A seating stem that contacts a bullet farther down its nosecone provides more stability during seating. It’s a greater surface area and that is another hedge against the potential for unwanted tilting.

seating stems compared
Contact area is better lower than higher. Here’s a standard stem next to a custom stem.

If you’re a Forster user, they have a custom seating stem option I have been increasingly using. Send a bullet and they’ll custom-made a polished stem that exactly fits it, and in the right place.

3. Start it Right
Can bullets be damaged in seating? Yes. Absolutely. Especially some of the thinner-jacketed bullets can get scuffed during seating, and the stem can leave a ring indentation on the ogive. Some swear that the ring indentation is not hurting accuracy; I say, “I don’t know, but it can’t help.” A stem that’s a little larger inside diameter, that’s also been smoothed to a gentle radius, will make the ring disappear. A good local machinist can help.

Lyman VLD chamfer tool
A more relaxed angle on the inside case neck chamfer eases bullet entry and reduces potential for jacket damage, and is also an asset to getting the bullet started in-line. This is a Lyman VLD tool.

One simple thing that results in a marked decrease in jacket damage is to put a more relaxed inside chamfer on the case mouth. Switching from a 45-degree cutter to one with a 20-degree, for instance, tool angle results in a deeper, smoother chamfer. This also overall reduces entry and seating effort.

Be nice to the bullet!

4. Case Neck Attention
This is related to every other point made so far. The more consistent case neck walls are, the ultimate result is a better centered case mouth, and that results in less chance that seating the bullet is going to try to move the case neck, and also less chance there will be unequal contact as the bullet enters the case neck (less abrasion).

Better concentricity, as said, means the bullet can start straight into the neck and then all the precision alignment built into the tools gets to show its merit.

This is where brass segregation (for wall thickness consistency or runout), outside case neck turning to improve wall thickness consistency, and initial choice on the brand of brass all come in.

Much of that also comes from the choice of sizing die and how well it’s been set up, and that’s been talked on in these pages before (and will be again, no doubt).

And, making sure the case neck cylinders are all the same heights makes a difference too, because that means each bullet is encased in an equal amount of material.

Check out dies at MSSS HERE
Find a chamfer tool HERE
Learn more about custom stems HERE 

The preceding is a specially-adapted excerpt from Glen’s book Top-Grade Ammo. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

RELOADERS CORNER: Seating Depth Issues

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Don’t take anything for granted! Safety and suitability are both at risk if you don’t take time to analyze and act on this important topic. READ MORE

land illustration

Glen Zediker

As said often, it’s sometimes recent experience that leads to my Reloaders Corner topics. Whether it’s a question I’ve been asked, usually, or, in this case, a malfunction I’ve had, those things are fresh in my mind. I hope to believe, and have to believe, that any such topics aren’t only a question for them, or for me.

That brings us to bullet seating depths, which really means overall cartridge length, using some particular bullet.

Usually, when we’re loading for a rifle with a box magazine, either bolt-action or semi-auto, the cartridge overall length — that’s measured from the base of the case to the tip of the bullet — defines and determines the maximum length. Usually.

What ultimately determines the cartridge overall length maximum, though, is really the first point of contact that the bullet makes (will make) with the rifling or lands ahead of the chamber throat. That space, and therefore overall round length, has a whopping lot to do with the chamber reamer specs, and also the reamer operator’s judgment in some cases, but we need to know.

It also can have a whopping lot to do with the bullet! And that’s what the most of this next is all about.

So here’s the lesson to learn, and, for me, to relearn: Do not assume that if the round fits into the magazine it will be fine. I will, at the least, freely admit to my mistakes because, one, I dang sho should know better, and, two, if I know better and still don’t do better confession is my punishment. Well, not really, but it’s always a wake-up call.

Different bullets have different profiles, different ogive architectures. The ogive is the “curve” beyond the last point up the bullet that’s caliber diameter (meaning full diameter) ending at the bullet tip. My slang but descriptive term for this is “nosecone.” Tracing up this curve, some point will be equal to land diameter. So where this point is on the seated bullet and where this point is ahead of it in the chamber matters a lot.

Unless it’s done as a deliberate tactic, there needs to be some space, some distance between the land diameter point on the bullet nosecone and the lands. The amount of that distance is referred to as “jump,” because that’s descriptive. It’s the gap the bullet has to cross through to engage into the rifling. Usually the closer the better, and that “tactic” used often by precision shooters (mostly long-range and Benchrest competitors) is to purposely seat the bullet so it’s touching the lands. That’s done in the belief that if there’s no jump, then there’s no ill effects from jump. It’s very often right, and I’ve proven that to myself many a time. It’s not always right, but then if it was this all would be too easy.

The reason there needs to be some space is because when a bullet goes from just off to just on the lands, pressure jumps. It’s a “spike,” not a surge, but it’s enough to put a load that’s nearing the edge over the edge. In something like a .223 Rem. it’s about a half-grain-worth of propellant.

hornady 52
Here’s one I messed up with. The ogive or nosecone profile on this bullet is much “higher” than normal for a match bullet of this weight and it encountered the lands at a much shorter overall length than any others I had used. I learned the hard way, even though I already knew better.

So. Here’s the lesson I learned again, but this one wasn’t my fault! Honest! Several years ago, however, here’s one that was my fault: new (to me) match bullet, a short 52-gr. I wanted to try for reduced-course NRA High Power Rifle events. Rifle had a Wylde .223 Rem. chamber. A Wylde has a throat length between a 5.56 NATO and a SAAMI-spec. .223 Rem. That means the throat is fairly much more generous than commercial .223 Rem. specs. The maximum cartridge overall length in an AR15 box magazine is 2.260 inches, and I go 2.255 for a margin. I checked some industry manual data for this bullet and did notice that the overall cartridge length listed in the data spec table was a good deal shorter than that. I quickly did some “math” but without numbers (so it wasn’t really math) and decided that since I had a longer chamber I’d ignore that and just seat the bullets to 2.255. Blew primers right and left.

Back home and gage in hand and, dang, they weren’t kidding! I was about 0.020 into the lands at that cartridge length. That’s a honking lot. That’s also ultimately dangerous because of the free-floating firing pin tapping off the primer when a round is loaded into an AR15. A bullet that’s getting jammed into the lands is greatly more resistant to chambering freely and fully.

I humbly learned my lesson.

Get a gage and use it! The best out there is the Hornady LNL Overall Length gage. This tool lets you very easily find the overall round length that touches the lands with your bullet in your barrel. Very valuable, that.

lnl oal gages
A Hornady LNL OAL Gage will show right quick like and in a hurry with the seating depth that touches the lands is with your bullet in your gun. Valuable!

Use it in conjunction with its companion “bullet length comparator” insert for the very best precision. That tool measures a bullet at a point on its ogive that (usually) corresponds closely with land diameter. It won’t be perfectly the same, but it doesn’t have to be. What matters is that it gives a more accurate figure. Avoiding the bullet tip in a measurement eliminates that (guaranteed, by the way) inconsistency in accurate measurement because of bullet tip variations.

LNL comparator
A “comparator,” like this one from Hornady’s LNL line, is a much more accurate way to measure seating depth because the bullet tip doesn’t get involved. I like the curved one: easier and more accurate by my experience.

Now. To the recent experience: It was with a .300 Blackout (AAC) subsonic. I did not have the means to gauge this using my tools (then, but I do now). However, that wouldn’t have mattered in this case, and why is next.

Tested a factory load. Liked it. Noticed nothing unusual. Functioned perfectly, shot well. Brought it home and filled a magazine, loaded one in the chamber, and set it aside. Folks, just so you don’t think I’m irresponsible, that gun is what I keep at the ready for home-defense. So, my son, who had gone in to unload and then dry-fire the gun, came up and said, “Dad. The bolt won’t open.” Dang. It wouldn’t. I started thinking up all reasons that might be behind that. The bolt carrier would retract a little way, which was the limit of usual “play” in the bolt travel inside it, so I didn’t think anything was broken. To remove the round I pulled off the upper, took it to the shop, and pried back the bolt carrier from the underside. A couple of careful but firm enough strokes and it opened.

The bullet had really jammed into the lands! I mean really jammed. Extracting the round and looking at it, land impressions were clear, and measuring the extracted round showed it was 0.022 longer than the new, un-chambered round. Unseating the jammed round pulled the bullet that far out from the case neck.

I manually inserted another round of the same into the chamber and gave it a nudge-in with my finger, and, sure enough, there it sat not nearly fully into the chamber. Had to tap it back out.

jammed bullet
Here’s the “stuck” round, right, talked over in the article. Land impression is pretty clear, and pretty deep. Notice also that the bullet got pulled out a might upon finally opening the action. On left is the same round out of the same box that was pushed into the chamber; land marks also, just a lot lower!

So. Since it’s a factory load, I really couldn’t have had a clue that it wasn’t compatible with my chamber throat. But now I do. And, for a clue, do that same yourself. If the round won’t drop in and out of a chamber fully and easily, that might be a problem. I still don’t know what the actual measured amount of the excessive length might have been. To find that I’d have to get a box of those bullets and gauge them using the LNL tools. I’m not going to do that. I’ve chosen another load that’s no-issues.

I say “might be” because, again these rounds functioned well, but, also, well, that can’t be good…

I suppose I will now need to start handloading for that contraption. I have also written down 100 times: “I will always check the chamber throat, even if it’s not a long-range rifle…”

Find gages at Midsouth HERE and HERE

The preceding is a specially-adapted excerpt from Glen’s book Top-Grade Ammo. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

RELOADERS CORNER: Case Trimmers

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An ideal case trimmer provides precision, speed, and affordability. Here are some ideas on avoiding compromise. READ MORE

Hornady Cam-Lok
Hornady Cam-Lock. Good trimmer at a fair price. See it HERE

Glen Zediker

At some point, or points, cases need to be trimmed to a shorter length. Brass flows. Therefore, a case trimmer is pretty much a given in the tool assortment for any handloader.

There are needs and wants, realities and ideals. That’s true with many things, and applies often to reloading equipment. Ideally, a case trimmer will go beyond just trimming the case to a shorter length. They all do that well enough. I think it’s important that a case has a square mouth — dead flat across the top. This is an asset to getting a bullet started well into the case neck during the seating operation.

A Good Trimmer
There are a variety of trimmers available from most of the popular industry tooling suppliers. And most follow a pretty similar form and formula: a little hand-cranked lathe. In these, the back end of the case is chucked into a collet-type fitting. A caliber-size pilot that’s centered in and surrounded by a cutting head goes into the case neck and supports the front of the case.

Not nearly perfect! There are a few reasons and sources for reduced precision. The tool alignment may be true at each “end” of the trimmer, but the case we’re working with probably isn’t true. Mostly, since there has to be a gap for the pilot to freely rotate, and since case neck walls aren’t all consistent in thickness, the fit isn’t close enough to prevent out-of-round rotation. Along with the inevitable case body warp there’s bound to be a tad amount of wiggle. Since the case is supported only at its head area, not by its body, there’s flex afoot.

None of that means the case neck won’t get trimmed to a shorter length, which is the general idea. It does, however, mean that it’s not liable to be perfectly squared up.

LE Wilson
LE Wilson. See it HERE at Midsouth.

A Better Trimmer
I rarely just overtly recommend one tool over all the others, but after a good many years working with case trimmers, I can and will tell you that the LE Wilson design is the best I’ve yet tried. I guess, yes, that is just opinion, but it’s really not.

The difference in this trimmer design is that the case is supported within a sleeve by its body. There’s no polarized suspension front and back. Mostly, there’s no pilot. The cutter on an LE Wilson faces off the front of the case squarely. The sleeve holding the case sit atop a pair of rails and the whole arrangement excludes case condition from the process.

le wilson sleeve
Tap it in… Then tap it out…

le wilson sleeve

So why doesn’t everyone use one? Honestly, I’m not entirely sure. It is a different arrangement, and it’s not cheap, especially not if you accessorize the fool out of it with a stand, a clamping device, and a micrometer. It’s not more than the other higher-end manual trimmers though.

It’s also fast! There’s no clamp-twisting to get the next case in place, and back out again. The sleeves are slightly tapered inside so the case is tapped in and then tapped out. With a little experience it’s amazingly quick to get through your block full of brass.

Flexibility
Virtually all case trimmers can provide additional utility, do different jobs. The cutter can be replaced with a reamer, and some can get reworked into outside case neck turners.

My choice is usually a stand-alone station, and that’s mostly because it’s pretty tedious refitting the appliances. I am, or at least have become, lazy.

forster case trimmer
Forster. This is a good choice especially for those who want to make a multi-purpose tool out of their base unit. There’s a big collection of add-ons that let work over primer pockets, turn case necks, ream case necks, and even hollow-point bullets. Its precision is better than most.
forster accessories
A a few of the things that can go on a Forster. Very versatile tool!

As with all said about alignment for case length trimming, that is also all the same for using a trimmer for other chores. And, yes, I still think the LE Wilson works best as a reamer, for instance, and that is because all the alignment precision is built into the tool itself; the case doesn’t play a role.

About options, by all means fit up a “combo-head” if it’s available that will finish the trim with a nice inside/outside chamfer/deburr. Big time saver. These can be a trick to get set just right, but it sure saves time.

Power
It sure is nice to get a break from the crank! There are, though, as I see it, two kinds of power case trimmers. Those that replace the hand crank with an electric motor and those that are designed from the start to be powered.

Some trimmers offer a means to add your own power source, like an electric screwdriver or drill.

Gracey Match Prep
Gracey Match Prep. Pretty much a big motor! It’s intimidating on first use, but just push the case in and it gets trimmed (and chamfered). It’s way quick in use and produces precise results.

My favorite proprietary power trimmer is a Gracey “Match Prep.” Designed by the late Doyle Gracey as a fast and easy way to trim huge quantities of Lake City brass for NRA High Power Rilfe shooters, it’s a serious machine. It works like a gigantic electric pencil sharpener, at least in spirit. Pick up a case and push it forward into a collar and it’s trimmed and squarely faced. No clamps or sleeves. The case shoulder stops against the inside of the collar, so it’s imperative that all cases are resized prior to use. As said last time, though, that’s really the only time you’ll get consistent results with any trimmer.

gracey holder
A key to a Gracey’s speed is that the cases stop on the case shoulder: just push it it!

I don’t know how many cases I can trim in an hour because I’ve never spent an hour using a Gracey. I can easily do 100 in under 5 minutes.

Another very good power trimmer is the Giraud. Its essential means for and in operation are about the same as Gracey but it is a nicer package with more features. Gracey is pretty daggone simple. That’s not all bad. I’d say Giraud is the best, and its price does reflect that.

One Last
Again, it’s important to evaluate the overall condition of a batch of cases, related to how many uses they’ve had. Having grown a little longer isn’t likely to be the only thing that’s changed in a case that exceeds whatever limit you set for it.

And, speaking of, the “trim-to” length is usually 0.010 inches shorter than the maximum SAAMI-stated overall case dimension.

Next time we’ll look at tools used to treat the trimmed case necks and finish this task in fine style.

Check out some more options at Midsouth HERE

Gracey
Giraud

The preceding is a specially-adapted excerpt from Glen’s book Top-Grade Ammo. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

RELOADERS CORNER: Case Trimming

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We all have to trim bottleneck cases sometime. Question is when and how much, and then “how,” and here’s a place to start. KEEP READING

case trimmer

Glen Zediker

After going through that last series on keeping up with changes in cases resulting from their use and reuse, “flow” was a culprit behind the majority of detrimental changes. That is: Brass flows during firing. It moves from where it was to somewhere else. Since there’s a finite amount of material in a case, one place is getting thinner and another is getting thicker. The sources of the material, where the flow starts and where it stops, are primarily case necks and case heads.

To completely finish up on all this, the most obvious indication that there’s flow is measuring case lengths from base to mouth.

case trimming
The primary reason to trim is to keep overly-long cases from overrunning their space in the chamber. If the case mouth encounters the end of its allotted space, it can pinch in on the bullet, elevating pressure. Now, there’s usually a good deal of leeway before safety can be a question, but don’t push it…
measure case length
A caliper is the only tool needed to measure case length. It’s not really necessary to measure each and every case each and every time. It’s a whopping lot faster to set the trimmer so it just touches the shortest case you have (revealed through the process itself in setting up the trimmer) and trim all the cases using that setting locked in place.

First, and very (very) important: The ONLY time to check case length, or to trim cases, is after they have been sized! A fired, unsized case will be shorter than it was going in. The reason is because of the expansion in the case that resulted from firing. When the expanded areas are squeezed back to spec by a sizing die the case gets longer as it gets smaller in diameter, same as rolling a ball of modeling clay out on a table. After sizing is also the only time we can we know that the case shoulder area is consistent in dimension.

You’ll see two length figures published for your cartridge of choice: maximum length and trim-to length. Published trim-to length is usually 0.010-inches under what’s listed as maximum.

I got a gage umpteen years ago that could indicate the maximum case length a chamber could accommodate — technically, a “chamber length gage.” Man. I checked the chambers in my main rifles and found that they were all well more generous than the SAAMI-maximum. That didn’t really mean a lot, in fact, to how I proceeded. And it also didn’t mean I can advise ignoring the potential for danger in exceeding SAAMI-maximum. It just pointed out that there are differences in chambers, gun to gun, and at least showed me that not exceeding max stated length should easily keep you safe.

chamber length gage

If a case got too long, exceeded the amount of room given to it in the chamber, that would be a safety problem! The bolt may not close fully. And, if it did, the extra length would create a pinching-in constriction, and that would spike pressure.

We can easily imagine that there’s an influence from relatively longer or shorter case necks in their influence in consistently encasing the bullet. And I’m sure we’d be right. Trimming cases all the same should mean that all the case neck cylinders are the same height. Someone looking to maximize accuracy is liable to get worked up about that enough to trim each firing. I trimmed my tournament cases each use. And, no, none were remotely approaching maximum length. It’s reasonable to further suppose that more or less retention will influence velocity consistency.

Another performance asset may or may not happen, depending on the trimming tool chosen. But. A good trimmer will square the case mouth. I’ve seen a many new cases with a “half-moon” cut after trimming. A square case mouth helps a bullet start and finish straight when it’s seated.

case trimmer
Not all case trimmers are equal. We’ll talk more about some I like next time, and I’ll tell you why.

My routine for this sort of “accuracy-oriented” case trimming is simple — tedious, but simple. I don’t measure each case. I just run them all through a trimmer set to “some” length. Some are trimmed more or less, some just show a bright scuff on one little bit of the case mouth, but they are then all the same length. If I can’t prove it in group sizes, it sho does set my mind at ease that all the cases are holding all the bullets more nearly the same.

For those rifles that aren’t tournament guns, the only concern is that none, indeed, become too long. Those I will check at that “4-firings-in” point. Some may have reached SAAMI-maximum, most won’t have, but all will be longer than when started. I start them at a figure close to suggested “trim-to.” Stop and think about it, and if there’s been overall a 0.010-inch length increase, that’s significant.

As with all things associated with use and reuse in semi-autos compared to bolt-actions, cases are going to grow more and faster in a gas-gun.

Another instance where it’s important to keep up with case lengths, and that, again, really has to do with making them all the same, is for those who crimp (with a conventional cannelure method).

Now, there’s zero harm in using a longer “trim-to” length, and that may be more popular than my method. These lengths are stated in reloading manuals. Keeping up with it over years, I’ve seen no difference in the rate of lengthening trimming longer or shorter; I trim “shorter” solely as a matter of consistency over the (short) life of my semi-auto cases.

Next time more about the tools.

Get started shopping HERE

The preceding is a specially-adapted excerpt from Glen Zediker’s book Top-Grade Ammo.

Glen’s books, Handloading For Competition and Top-Grade Ammo, are available at Midsouth HERE. For more information about other books by Glen, visit ZedikerPublishing.com

Glen’s newest book, America’s Gun: The Practical AR15. Check it out HERE

par15