Category Archives: Reloading Corner

RELOADERS CORNER: Standard Deviation

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Improving longer-range accuracy has a lot to with consistent bullet velocities. First comes understanding it! Here’s a start on it… KEEP READING

chronograph

Glen Zediker

It’s springtime (finally) and one of the things on your list might be working up a load for a new rifle, or new bullet. I’ve talked about testing processes and procedures, and also some about those bullets, and especially those with higher ballistic coefficients. The more aerodynamic bullet, by itself, is no guarantee of a smaller group (and whether you’re shooting one shot or 20 shots, you’re always shooting a group…).

To make the “magic” of a high-BC bullet come to life, they all need to be arriving at the destination at really close to the same speed. On target, that’s all about elevation consistency. It’s pretty commonly accepted among long-range competitive shooters that points losses come more from errant high and low impacts than from missed wind calls. High-BC bullets traveling at more consistent speeds reduces dispersions in all directions. But only if they’re traveling at consistent velocities!

The first step to improving velocity consistency is getting a good way to measure it. That there would be a chronograph. Nowadays especially, there are a number of simple-to-use and inexpensive chronographs available, that are accurate. Some have more features, which mostly revolve around providing printouts, digital records, and calculations, but what matters most (to me at least) is one that lets me easily read the velocity of each shot.

Check Misdouth offerings HERE

MagnetoSpeed
The newer barrel-mounted electro-magnetic chronographs make it really easy. I like the idea of being able to chronograph from shooting position, not just from a benchrest. This is a MagnetoSpeed.

So. What’s next is understanding the terms associated with this area of data-gathering.

“Standard deviation” (SD) is the most common measure of shot-to-shot consistency. It reflects on the SD reflects on the anticipated consistency of bullet velocities (some number of recorded velocities). The “standard” part reflects on a sort of an average of the rounds tested.

[Phrases like “sort of” upset mathematically-oriented folks, so here’s the actual definition: SD is the square root of the mean of the squares of the deviations. More in a bit.]

I pay less attention than many to standard deviation because: I don’t think standard deviation is near as important as is the “range,” which is the lowest and highest speeds recorded. Another that matters is “extreme spread,” which, by definition, is the difference between this shot and the next shot. I watch the speed on each shot. I compare this one to the next one and to the last one, and, as said, find the highest and the lowest.

Why? Well because that’s how I shoot tournament rounds. This one, then another, and another. A low velocity difference means that the accuracy of my judgment of my own wind call has some support.

standard deviation
Standard deviation calculation forms a bell curve. 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. So? Watch each shot. That’s the way to know how a load performs with respect to velocity consistency. SD allows you to estimate how likely it is for “outliers” to show up.

A load that exhibits a low SD is not automatically going to group small, just because a low SD. I’ve had Benchrest competitors tell me that sometimes their best groups don’t come with a low-SD load, but do not apply that to greater distance! At 100 yards a bullet’s time of flight and speed loss are both so relatively small that even what some might call a big variation in bullet velocities (+/-25 fps or so) isn’t going to harm a group, not even the tiny groups it takes to be competitive in that sport. On downrange, though, it really starts to matter. (And keep in mind that “it” is a reference to velocity consistency, whether denoted by SD or otherwise.)

For an example from my notes: Sierra 190gr .308 MatchKing. Its 2600 fps muzzle velocity becomes 2450 at 100 yards and 1750 at 600 yards. (These numbers are rounded but serve for a example.)

If we’re working with a just awful 100 fps muzzle velocity change, that means one bullet goes out at 2550 and the next leaves at 2650, in the worst-case. The first drifts about 28 inches (let’s make it a constant full-value 10-mph wind to keep it simple) and the next slides 26 inches. But! Drop… That is THE factor, and here’s where inconsistent velocities really hurt. With this 190, drop amounts over a 100 fps range are about three 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’s going to cost on target, big time. And it gets way, 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). Now, it’s unusual for a wind to be full-value and dead constant, so on-target left and right displacement is even relatively less — but elevation displacement is consistent regardless.

So, my 100 fps example is extreme, but half of that, or a quarter of that, still blows up a score, or an important hit on a target.

propellant charge consistency
This is probably the most influential factor in improving SD: consistent propellant charge. It’s not only that each case has an identical powder load, though, because primer factors, and finding the right combination ultimately is why we do all the testing…

So what’s a tolerable SD? 12. There have been, rest assured, much calculation to lead  up to that answer. That’s the SD that “doesn’t matter” to accuracy, meaning it’s not going to be the leading factor in a miss. It’s more than I’ll accept for a tournament load, but for those I’m looking for an extreme spread never more than 10 fps (the range might be higher, but now we’re just mincing terms). More later…

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

RELOADERS CORNER: Bullet Ballistic Coefficient

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Ballistic coefficient is a term that’s often used but sometimes not fully understood. Keep reading to find out exactly what it is, and what it isn’t…. HERE

nosler rdf
BC is essentially a race between a real bullet and a mathematical bullet. Real bullet never wins… The closer the real bullet gets to the “standard” bullet, though, the higher its BC and the better it’s going to fly. I’d love to get a Kroger-sack full of G1s… Until then, one of these Nosler RDFs will do nicely.

Glen Zediker

A “ballistic coefficient,” or “BC,” is a number that suggests a bullet’s aerodynamic performance.

BC is a component in bullet design that matters much, and it matters more the farther it travels. Bullets that flat out fly, fly flat far out, are of great interest to any longer-range shooter. A bullet with a high(er)-BC is also an advantage at shorter distances, especially when there are variations in the shooting distance. A flatter-shooting (one of the traits supported by a higher BC) bullet means a more flexible zero, a smaller difference in the elevation hold from, say, 100 to 300 yards. BC is influenced by sectional density, bullet weight, and, mostly, its shape or profile.

BCs are derived by comparison. Here’s how that works: There are “standard” bullets that are mathematical models. Bullet designers and ballisticians know which model to apply to different bullet styles. Pistol bullets, for instance, are calculated from (compared to) different models. For the majority of rifle bullets we’ll encounter, one common model is a “G1” (there are others, like 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 doesn’t exist in a tangible sense.

vld blueprint
Here’s a bullet blueprint. It’s the Bill Davis original 105gr 6mm “VLD” (very low drag). Design factors that influence BC are pretty much every design factor: length, ogive, boat-tail, meplat, weight. All these factors, in this instance, calculate a BC of 0.560. By the way, there’s about a 5 point BC increase for each added 1 grain of bullet weight.

The standard bullet has a BC of 1.000. An actual bullet that’s compared to, for example, the G1 at points, distances downrange, will either be flying faster or slower than the G1 model. If it’s faster, its BC will be greater than 1.000; if it’s slower, it will be less than 1.000. So it’s a percentage of the standard or model bullet’s performance.

Comparing bullets with different BCs, the one with the higher number loses less speed over distance. Losing less speed means its flight time will be shorter and it won’t drift and drop as much as will a bullet with a lower BC. So, a 0.600 flies better than a 0.550.

Depending on the bullet-maker, assigned or published BCs are either calculated or measured. More mathematics than I can wrap my mind around can get these calculations done based on a blueprint. Measured BCs involve chronographing at the muzzle and then at other points on downrange, same bullet, same flight.

Which method — math or measure — provides the best information? Some, and this only “makes sense,” believe that a measured, tested BC is more realistic and, therefore, more valuable. But, if the point is to compare bullets, calculated BCs might be more reliably accurate. I know a number of very serious NRA High Power shooters who have gone to great lengths to “field test” different bullets. It’s not easy to chronograph at long range. Given that information, measured BCs are quite often lower, but not nearly always. Reasons follow.

All the drift and drop tables (whether printed or digital) you’ll see are based on a bullet’s assigned BC. The accuracy of those tables clearly revolves around what the actual, at that moment, BC performance is from the bullet you’re shooting. Also, some bullets have a different stated BC based on muzzle velocity to start.

A whopping lot of things affect the actual, demonstrated BC: anything that can influence bullet flight influences the actual BC performance.

Bullet stability is 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 BC outcome.

Atmospherics, which add up as a list of factors, influence BC mightily. 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 BC as do any conditions that serve to hinder its flight. BCs are based on sea-level so can easily show as a higher number at a higher elevation.

uniformed meplat
BC uniformity is important to a long-range shooter’s score (less elevation dispersion results). There will be variations in any box of hollowpoint match-style bullets, and a source for variation is the meplat (tip). These variations are the result of the pointing-up process in manufacture. I’ve measured as much as 0.020 inches sorting through a box of 100. A “meplat uniformer” tool eliminates this variance. Uniforming reduces BC 3-4 points, but it’s a trade many serious long-range shooters say is worth the effort. Uniformed on right.

meplat uniformer

Range-realized 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. If you’re interested, there’s some valuable information from David Tubb (visit DavidTubb.com). He’s done a volume of work on calculating influences from atmospherics as it applies to his DTR project, which, in one way of seeing it, gets down to understanding why it’s really rare to dial in what a ballistics table says for a particular bullet and speed and distance, and hit the target.

One last (for now) bit of information I’ve always found valuable: a BC is a finite thing in one regard, and that is that any BC derived from a G1 model, for instance, fits all bullets with that same BC. This was helpful before ballistics apps were as common and easy as they are now. For instance, if there was a new .224-caliber bullet with an advertised BC, but no tables, just find another bullet, of any caliber, with that same BC, plug in the velocity, and the drift and drop figures will be accurate.

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

RELOADERS CORNER: Bullets 101

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Bullet structure should play an important part in your selections. Here’s a short course in bullet architecture, and why it matters!

224 bullet comparison
There’s probably a wider variety of .224 caliber bullets than any other diameter, and there are whopping differences available! Left is a Hornady 35 V-Max, right is a JLK 90gr VLD. That’s the longest .224 I’ve had to work with.

Glen Zediker

These days we don’t have to settle for much of anything. Pretty much whatever it is, there are options. That’s a good thing, as long as we figure out how to sort through all the options. I didn’t count them all, but there are way on more bullets available now than ever. This article sets out to help you all understand the essential engineering of this all-important ammo component.

The reason there are so many bullets is because there are so many different ultimate uses we put them to.

All bullets are designed or intended to do something, and, clearly, the first idea is to hit a target.

There are bullets engineered to perform variously on target, including the proximity of impacts on target. I say it that way because a “match” bullet’s job is to perforate a piece of paper. A bullet designed for varmint hunting, on the other hand, is designed to produce explosive impact, and one for larger game hunting strives to strike a balance between expansion and penetration. All bullets have to meet their target to be effective, and different premiums often also result in a few trades. Specialty hunting projectiles, for instance, don’t usually out and out group as well as those engineered for target shooting.

However! No matter how it’s built inside, there are universal elements of any bullet design, and those are found on the outside.

bullet parts
Here are the pieces-parts of a bullet. Each element is influential not only in downrange performance, but also in how tolerant or flexible the bullet will be in different rifle chamber and cartridge structures.

Bullet parts: base, that’s the bottom; boat-tail, or not (flat-base); shank, portion of full-caliber diameter; ogive, the sloping “nosecone,”; tip, either open or closed (open it’s called the “meplat”). The shape of the ogive and the first point of “major diameter” are extremely influential elements. The first point of major diameter can vary from barrel brand to barrel brand because it’s the point on the bullet that coincides with land diameter in the barrel — the first point that will actually contact the barrel as the bullet moves forward. When there’s a cartridge sitting in the rifle chamber, the distance or gap between the first point of major diameter and the lands is called “jump,” and, usually, the less there is the better. More in another article.

bullet bearing area
This gives an idea of bearing area. The point that contacts the lands is the first point of “major diameter,” and from there back down the body is what will be in contact with the barrel. Longer area means more tolerant behavior, but lower potential velocity.

The first point of major diameter and the shank combine to determine the bullet “bearing area.” This is how much of the bullet is riding the barrel surfaces. Usually, bullets with greater bearing areas tend to shoot accurately, but, might not get to velocities as high as one with a shorter bearing area. Longer bearing area creates more drag in the bore. Longer bearing area bullets also tend to be more tolerant of jump.

magazine box rounds
This is the round architecture that matters the most to the most of us. We need good on-target performance from cartridges with bullets seated to feed from a box magazine. Choose a tangent profile that’s no more than 8-caliber ogive.

The two essential profiles a bullet can take are “secant” and “tangent.” This refers to the shape of the ogive. A tangent is a more rounded, gradual flow toward the tip, while a secant is a more radical step-in, more like a spike. Secants fly with less resistance, but tangents are more tolerant of jump.

tangert and secant
Tangent, left; secant, right. Tangent ogives are more tolerant of jump, but not quite as aerodynamic at extended distance.

Ogives are measured in “calibers.” That’s pretty simple: an 8-caliber ogive describes an arc that’s 8 times caliber diameter; a 12-caliber is based on a circle that’s 12 times the caliber. The 8 will be a smaller circle than the 12, so, an 8-caliber ogive is more “blunt” or rounded. (So I don’t get comments from engineers, there’s more to it than this, as it applies on blueprints to different profiles; it’s the ratio of its radius to the diameter of the cylinder. But my description is accurate as an overview.)

Bullets with lower-caliber ogives are more tolerant of jump and (usually) shoot better, easier. Higher-caliber ogives fly better, farther. This is an important component in the “high-BC” designs. Same thing comparing tangent and secant: the first is easier, the second beats the air better.

bullets compared
Here’s a good example of the differences in bullets. These are both 75 grains. The one on the left is engineered to be fired from a magazine-length round; the other is engineered to provide better performance over more distance, and it should not be fired at magazine-length. Look at the ogives closely and see the curve difference.

When you see terms like “magazine bullet” or “length-tolerant bullet” that is referring to those with tangent profiles and lower-caliber ogives. (“Length-tolerant” means that it’s not sensitive to seating depth.) If you want to experiment with the longer “high-BC” style bullets, you might find they don’t group well until they get close to or right on the lands when the round is chambered.

More soon…

Check Midsouth for a massive selection of bullets of all calibers HERE

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

RELOADERS CORNER: Pressure Signs

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We usually want the most velocity we can SAFELY get, and here’s all about how to stay safe. Keep reading!

Glen Zediker

I’ve been on the topic of load development — “working up” a load — for the past couple of editions, and, based on the excellent feedback from you all, here’s more. As always, there’s only so much I can write before I have to cut myself off.

I’ve said that velocity is the initial leading indicator of pressure. Velocity, in itself, however, is not a definitive indicator of pressure. I’d like to clarify… The first point is that I am a big believer in establishing a goal for load development, and, for me (and likely most others) that is a velocity. Accuracy is a given! I will never consider a combination that’s not shooting little knots downrange, but accuracy and velocity are not mutually exclusive. I also would never consider a combination that produced very small groups at an unacceptably low velocity, and that’s because I’m shooting (always) beyond 200 yards. The super-accurate low-velocity load gets its bullet shifted that much more in a variable wind, so it’s way on less likely to maintain those small groups.

I want to hit the velocity ballpark I have in mind and that’s why chronograph readings as I’m incrementally increasing the propellant charge are my leading indicator to how close I’m getting. I am also, always, looking for pressure signs on the spent cases — each and every one ejected.

So about those pressure signs…

Primer condition gets first attention.

primer pressure signs
Middle is what I want to see: pretty much a new primer with a nice round dimple in the center. Right, well. Massive pressure! But notice that the primer still shows a radius on the edges and is only a little rougher in appearance, well, aside from the crack…

A primer should have a smoothly dimpled firing pin indention, a shiny appearance, and a visible radius on its edge. If any of those are missing or compromised to varying degrees, there’s your sign… A dull and flattened primer has been abused, as well as one with a pitted or cratered appearance. Clearly, a crack or leak (indicated by black fouling) is way over the limit. After experience, backed up by gauged measurements, you’re liable to find that judging what’s “normal” and “safe” from one rifle can be different from another. I have had individual guns that flattened primers at any point near a safe-maximum charge. And, I’ve had them that just lied. Unfortunately, small-rifle primers don’t show always show pressure signs as reliably as large-rifle primers (structural differences). I’ve had experiences where the primers are all nice and shiny like and then blow out with the next increment. Shame on me for taking it there, and, speaking of: don’t get greedy! That’s one reason a velocity goal is important. Despite what your kindergarten teacher told you, you’re not that special… If you’re reading another 50+ feet per second more than what consensus says you should, better bet you’re over-pressure. “We” went through a lot of that when coated bullets got popular: those changed all the rules for “maximums.”

flattened primer
Here’s flat. My experience has been that large-rifle primers tend to display this indication more so than small. What’s happened is that the primer has flowed quite forcibly to fit the confines of its pocket and the bolt face. It’s also normal for some rifles, but that just means you have to know: pay attention and back off if you see a flattened primer.

The best pressure indicators show at the loading bench.

primer seating
My best “gage” for pressure is seating a primer in a fired and resized case. It’s a feel, gained through comparative experience, but too easy means there was too much pressure.

The reason I suggest (strongly) doing load work-up with new cases is because you then have a baseline. Measure the case head diameter (on the case, not the rim or groove) on the new case and compare it to the fired case. Up to 0.0005 (that’s ten-thousandths) is really high but some say acceptable (not me), and 0.0002-0.0003 is what I’d prefer. Plus, since a new case is at its smallest, meaning it will have a little less capacity than a fired case, you’re getting some assurance that the pressure will likely be a little lower from the same load in subsequent reuses of that case.

All dimensions are at their minimum in a new case. Primer pocket expansion is related to case head expansion. I get (what’s proven to be) a very accurate indication of pressure based on the resistance to seating a primer in that resized case. You have to use a priming tool that gives adequate feedback (meaning low leverage) but if the primer just slips right back in, that load was over-pressure. In a more extreme circumstance, the primer won’t stay seated. Yes. I have seen that. Shame on me, again.

Finally, a new case easily points out the difference between a “pressure ring” and a “sizing line” that can show just above the case head along the case body. A bright ring there indicates excessive stretching (a sizing line comes from the die reducing that area, and is perfectly normal). That “pressure ring” sign is also likely an “improper headspace” sign, but that’s another article.

pressure ring
Here’s a “pressure ring.” This poor old fellah used to be a brand-new Lake City Match case. I suspect there was some issue with this rifle’s headspace, but if you see this bright stretch mark, red flag it! It means the case is going to crack right there next use (called an “insipient head separation”).

Pierced Primers
This is a common malady on AR-platform guns, and especially on the big-chassis versions (SR-25, AR-10, and similar). Pressure both isn’t and is the culprit and the solution. Lemmeesplain: What causes the pierce is a firing pin hole that is too large. It is not the fit of the firing pin tip to the hole! An engineer can explain it, but it has to do with surface area covered by the firing pin hole, and then along with it the surface area of the primer. Simply: the firing pin hole turns into a cookie cutter. A primer pierce creates all manner of ills, including wrecked firing pins, gas flow through the charging handle area (where your face is), and abrasive debris scattered throughout the lower interior, including the trigger parts.

firing pin hole size
Blueprints call for a 0.058-inch diameter firing pin hole on an AR15 bolt. If the hole is too large then primer structural failures (pierces) will, not can, rear up. Too big is anything more than 0.062 inches, and I’ve seen plenty bigger than that. I use machinist’s drill bits to quick-check bolts: 1/16 (0.0625) and #53 (0.0595). If the first fits the hole, find another bolt. If the #53 won’t go, use that bolt with confidence.
pierced primer
Notice that this primer doesn’t really show excessive pressure signs. Just has a hole in it…

Excessive pressure gets blamed for a pierce but what’s really going on there is that it’s not certain that amount of pressure would be judged as “excessive.” It’s just gotten high enough to bring on this result. So, yes, lightening the load will stop the piercing, but, in my experience and that of many others, the pierces can start happening before reaching what most might agree on is a max load. I say that because “we” are all shooting about the same bullet/primer/case/propellant combinations in NRA High Power Rifle (with respect to Service Rifle division AR15s, for instance). Seeing pierced primers before hitting the proximity of competitive velocities points to “something else,” and that is the firing pin hole.

In a truly over-pressure load, the primer can crack or blow slap out, but it won’t pierce.

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

RELOADERS CORNER: Incremental Load Work-Up

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To get the most from your load testing, in the shortest time possible, learn the “Audette Method,” and put it work for you. Here’s how!

sight in target
Use a target that’s, one, easy to line up on, and, two, lets you make notes on the target itself. I usually circle and note the 3-shot increments, or you can add a number by each shot hole to indicate which try they belong to. Midsouth has some HERE

Glen Zediker

Last edition I suggested taking the step toward putting together a “portable” loading setup to allow for load development right at the range. This time I’ll talk about an idea on getting the most out of a test session in the quickest and surest way.

I have followed an “incremental” load work-up method for many years, and it’s served me well. Some call it the “Audette Method” named for the late and great Creighton Audette, long-time long-range and Benchrest experimenter.

Backing up a bit: Being able to employ this method efficiently requires having spent the preparation time, doing your homework, to know exactly how much “one click” is worth on your meter. Whether the meter clicks or not, it’s the value of one incremental mark on the metering arm. The value of that click or mark varies with the propellant, but by weighing several examples of each one-stop variation (done over at least a half-dozen stops) you’ll be able to accurately increase the charge for each test a known amount.

harrell's meter mounted
I count on a Harrell’s Precision meter. Its Culver mechanism allows for easy and accurate incremental adjustments in working up a load. The dryer sheet eliminates static electricity.

I usually test at 300 yards. That distance is adequate to give a good evaluation of accuracy and, for the purposes of this test, is also “far enough” that vertical spreads are more pronounced. Testing at 100 yards, sometimes they all look like good groups… So it’s at about 300 yards where we’ll start to see more difference in good and bad.

Get to the range and get set up, chronograph in place. Put up a target. Use whatever gives you a clear aiming point, but it’s helpful to have a light background not only to see the holes easier using a scope, but also to make notes on. More about that in a minute.

Use the same target for the entire session. (Put pasters over the previous holes if you want, but don’t change paper.) The reason for using the same target for the whole session is that helps determine vertical consistency as you work up through successively stouter propellant charges.

I fire 3 rounds per increment. As it gets closer to “done,” I increase it to 5 or 6. At that point I’ve hit a couple of speed points, two or three increments that represent a performance level I can live with (one is on the “iffy” end of the pressure, and I rarely choose that one) and am focusing more closely on group size. Final confirmation comes with one 20-round group. For what it’s worth, I usually pick the one in the middle.

A 3-round volley might seem inadequate, but it’s not if there’s confidence that the rounds are being well-directed and speed is being monitored. If I’m seeing more than 12-15 fps velocity spreads over 3 rounds, I’m not going to continue with that propellant. Same with group size: if it’s a big group over 3 rounds, it’s going to be a bigger group later on.

I’m sho no mathematician-statistician, but from experience I’ve found that, while certainly there’s some probability that the first 3 rounds fired might represent the extreme edges of the load’s group potential, and that all the others are going to land inside them, uhh, that’s not even a little bit likely. If it starts bad it finishes bad. On the contrary: no, just because the first 3 shots are close together and the velocity spread is low doesn’t mean it’s not going to get worse. Groups normally get bigger and velocities get wider, but, we have to start somewhere. It’s a matter of degrees. Also, the quality (accuracy) of the meter factors, and the better it is the better you can judge performance over fewer examples. And this is new brass, so that’s going to minimize inconsistencies further.

I can also tell you that it’s possible to wear out a barrel testing. No kidding.

Back to the “incremental” part of this test: As you increase the charges, bullets impact higher and higher on the target paper. You’re looking for a point where both group sizes and impact levels are very close together. If the groups are small, you won! That’s what Crieghton called a “sweet-spot” load, and that was one that didn’t show much on-target variance over a 2-3 increment charge difference (which is going to be about a half-grain of propellant). The value of such a load is immense, especially to a competitive shooter. It means that the daily variations, especially temperature, and even the small variances in propellant charges that might come with some propellants through meters, won’t affect your score. It’s also valuable to a hunter who’s planning to travel.

audette method loading
Audette Method: If it would only always work this way… This actually did work as shown so I captured and recreated it for posterity. The numbers on the left represent approximate propellant charge weights and the lines each indicate one click on my Harrell’s powder meter, a value about 0.15 grains of the propellant used in this test. Going up two clicks at a time for eight tries took me from 24.0 grains to about 26.0, which is a good range from a reasonable starting charge to pressure symptoms. I didn’t add in the velocities since that’s inconsequential to this illustration, but will say that “8” was too much and I settled on “6.” To make more sense out of this illustration, that ended up being 25.5 grains — step 6. I also went up using three rounds and skipping ahead by adding more clicks to the meter after viewing the (low) speeds on the first three groups (that’s why there’s no number 4 step; I went from step 3 to step 5). This has a lot to do with intuition sometimes. Point is, and should be, that here’s how the “Audette Method” is supposed to work: impact elevation on target goes up (these were fired at 300 yards) with charge increases, groups get smaller (hovering around two inches for this test) and stay small, and then elevation begins to stabilize. Choose a load that’s within this range. Then it’s a “sweet-spot” load. If this happens in your test, ask for no more!

That was the whole point to following this process. First, and foremost, it’s to find a good-performing load. It’s also how you find out if the propellant you chose is going to produce predictably. I can also tell you that I have chosen a propellant and a load using it that wasn’t always the highest speed or even the smallest single group. It was chosen because it will shoot predictably all year long. I base everything on the worst group, biggest velocity spread, not the smallest and lowest. If that doesn’t make sense it will after a summer on a tournament tour. If the worst group my combination will shoot is x-ring, and the worst spread is under 10 fps, it’s not the ammo that will lose the match…

As said to start this series, I started loading at the range because I got tired of bringing home partial batches of loser loads. And, you guessed it, the partial boxes usually contained recipes that were too hot. The only way to salvage those was to pull the bullets. Tedious. Or they were too low, of course, and fit only for busting up dirt clods. Plus, I’m able to test different charges in the same conditions. It’s a small investment that’s a huge time-saver.

If you do invest in a portable setup, exploit potentials. The possibilities for other tests are wide open, seating depth experiments, for instance.

CHECK OUT MORE TARGETS AT MIDSOUTH HERE

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

RELOADERS CORNER: 3 Helps For Easy Load Work-Ups

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Read this before you start the process of working up a load for your new rifle! It could save you huge amounts of time and money… Find out more!

Glen Zediker

Spring is around the corner. Well, if you walk way out into the street and squint really hard you can at least think you see it… Well it’s coming soon enough, at least, now’s a good time to get ready.

I never have been big on the personal value of published load data. The data I’m referring to is that from propellant and other component manufacturers, and also from articles done by independents. I think all such information, at most, provides a place to start, and it also gives some ideas on tendencies and cautions, and provides means for comparisons. But. I don’t think it can be taken straight to the loading bench with any guarantee of success, or of attaining “advertised” performance. And I say that not because I don’t think these folks don’t know what they’re doing. They do! It’s because, after way more than enough experience in proving myself right, I can tell you absolutely that their rifle is not your rifle! Neither, necessarily, are their propellant, primer, case, or bullet. Always take careful note of the barrel and components used for any published test data, and compare them to yours. In later comparisons of my notes with published data, sometimes I’m higher, often times I’m lower, and enough times I’m way lower… That’s the main concern there.

It’s not at all difficult to learn to develop your own loads, to essentially write your own loading manual.

To do this efficiently, you need to learn to load at the range. Right, right there near to where you’re testing. An unremarkable investment in a few tools and a little creativity can provide a way to take your show on the road.

Lee press mounted outdoors
You don’t have to invest a fortune to take your show on the road. A C-clamp and one of these little Lee Reloader presses is all you need! And a good powder meter. One with a clamp is handiest, or just mount it to a piece of wood and clamp that down (even a pickup tailgate works just fine). One clamp is adequate on the press since bullet seating is all in the “down” direction and not much force is needed.

The reason to do this is because it provides a way to precisely chart results. It’s a more reliable and accurate way to proceed. Otherwise, the option is to load varying charges at home and then see what happens at the range. That’s okay, but not nearly as good as on-the-spot experiements. Plus, you won’t have left over partial boxes of poor-performing rounds. It’s more economical and way on more efficient.

The preparation part, and this is what you might spend the remaining cold month or two working on, is, first, to get the tooling ready and, second, and most important, to start making notes on your powder meter.

Important: To be able to work up at the range, it’s mandatory that you’re using a meter that has incremental adjustment. Either a “click”-type “Culver”-style insert or, at minimum, a micrometer-style metering arm. You’ll be relying on the meter, not scales, to progress upward in propellant charges, and you absolutely have to know what the values are for each increment using the different propellants you plan to test. That is where you’ll be spending time prior to doing your homework. It’s well worth it! It can be a nightmare trying to get scales to read accurately outdoors, including the digital type.

Harrells meter mounted outdoors
I map out the incremental values of each click on my Harrell’s meter adjustment drum with the propellant I’ll be testing, and it’s really easy to step up each trial with confidence. I carry the whole kit in a large tool box.
Harrells meter close up
This is a Culver insert. It’s a huge help in following this process. It’s precise and repeatable.

Equipment List and Set-Up
When I need to do load work, I size, prep, and prime new cases and put them in a cartridge carrier (usually a 100-round box). I then pack up my little press, seating die, my meter, some cleaning gear, C-clamps, and my propellants. The press and meter and cleaning gear go in a tool box. I usually carry the propellants in a picnic-type cooler. And, very importantly, my chronograph. A notebook, some masking tape, and a sack lunch… I might be there a while.

Always (always) use new cases for load work-up.

When I get to the range, I’ll clamp-mount my press and meter to a bench, get out all the rest, and set up the chronograph. Take a target downrange and tack it up. I test at 300 yards, unless the load is intended for shorter-range use. I initially test longer-range loads at 300. Maybe I’m lazy, but longer-range testing is a tad amount more tedious. I’ll come back for that after I have a contender or two.

Working Up The Load:
The reason it’s a “work-up” is clear enough: we’re almost always looking to get the highest velocity we can, safely. High velocity, or higher velocity, is usually all-good. Shorter flight time means less bullet drift and drop, and a harder hit.

So working up means increasing propellant charge until we’re happy: happy with the speed and also that the cases will still hold water. (And more about that next time…)

blown primer
Keep track of the cases in the order they were fired. This helps later on when the effects can be measured. This little outing here, though, didn’t require a gage to cipher: a tad amount hot on that last little go around (last case bottom row on the right). Thing is, I didn’t load a whole boxfull of those chamber bombs to take with me, and that’s the beauty of loading right at the range.

Very important: it is vitally necessary to have established a goal, a stopping point, prior to testing. That is one of the functions of published data. That goal is bound to be velocity, not charge weight. And that, right there, is why you’re working up at the range: you want to get “advertised” velocity and need to find the charge weight that produces it.

I work up 0.20 grains at a time. Sometimes it’s more if I’m reading an unuseably low velocity on the initial trial. Since my meter has a “Culver”-style insert, which I trust completely, I reference its number of clicks in my notes rather than the grain-weights (a Culver works like a sight knob, and reads in the number of clicks, not the weight itself). I check the weights when I get back, and I do that by clicking to the settings I found delivered, and then weighing the resultant charges. Otherwise, just throw a charge into a case and cap it with masking tape (clearly labeled).

It’s not necessary to fire many rounds per increment. “Mathematically” 3-5 rounds is a stable enough base to reckon the performance of one step. Of course, I’ll be shooting more successive proofs-per-trial once I get it close. Some folks, and especially competitive shooters, wear out a barrel testing loads. That’s not necessary.

Here are 3 things I’ve found over the years to better ensure reliable results. Learned, of course, the hard way.

1. Limit testing to no more than one variable. I test one propellant at a time, per trip. If you want to test more than one on one day, bring the bore cleaning kit and use it between propellant changes. Results are corrupt if you’re “mixing” residues. Same goes for bullets. Otherwise, though, don’t clean the barrel during the test. I fire my most important rounds after 60+ rounds have gone through it, so I want a realistic evaluation of accuracy and velocity.

2. Replace the cases back into the container in the order they were fired. This allows for accurate post-test measurements. Use masking tape and staggered rows to label and identify the steps. I use 100-round ammo boxes because they leave enough space for the tape strips.

3. Go up 0.20 grains but come off 0.50 grains! If a load EVER shows a pressure sign, even just one round, come off 0.50 grains, not 0.10 or 0.20. Believe me on this one…

Check out chronographs HERE
Take a look at suitable meters HERE

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

RELOADERS CORNER: Neck-Only Case Sizing

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Neck-only resizing is an option for the bolt-action owner. Here are some ideas on why it works, and when it works best… Keep reading!

winchester bolt action
Neck-only sizing is for bolt-actions ONLY.

Glen Zediker

Cartridge case re-sizing is one of those topics that draws lines and forms camps. I am a big believer in full-length sizing, for any action type or use, and just saying that immediately draws argument.

Before getting into the “whens” and “whys” respecting full-length or neck-only sizing, here’s one that I think is an absolute: cases for reuse in a (any) semi-automatic should be full-length sized; neck-only sizing is only for bolt-actions. Having established that, all this next really only relates to what’s possible with a bolt-gun.

Backing up a bit: a “full-length” sizing die is one that returns the cartridge case body (and shoulder, if adjusted to do so) to near-to-new dimensions. A “neck-only” sizing die doesn’t touch the case body (and may or may not be able to touch the case shoulder). A full-length sizer also sizes the case neck, and, normally, the entire height of the case neck cylinder. A neck-only die can be adjusted to contact the height of the neck cylinder in various amounts.

hornady neck sizer
A neck-only sizing die doesn’t touch the case body, so there’s no reduction in case body diameter. This die can be adjusted to contact the case shoulder, and setting back the shoulder may still be necessary. Make sure you check cartridge case headspace!

The idea behind a neck-only die is to preserve fired case dimensions: make the case a closer mirror of rifle chamber dimensions. One advantage of neck-only sizing comes to those who expect, or need, to get a good many loadings from their cases, since this approach minimizes case stretching on subsequent firings.

However, the primary flag waved by neck-only fans says that it produces the best accuracy, and that full-length sizing is a compromise, favoring function over accuracy. I do and don’t agree, and the rest of this article I hope will clarify what I just said…

The reason I do and don’t agree is that I know folks who cannot get a good group unless they neck-only size, and I know other folks, and I’m one of them, who get very small groups following what many would say is “over-sizing” their cases.

forster neck sizing set
Here’s a nice set for neck-only sizing. The “bump” refers to the capacity to also contact the case shoulder to control its dimension, if wanted.

I believe that the main influence in realizing the virtues of neck-only sizing has a whopping lot to do with the rifle chamber. Specifically, factory-made, off-the-shelf bolt-actions tend to have relatively more generous chamber dimensions, as will many older surplus-sourced rifles. “More generous” is in reference to the tolerances established for the SAAMI blueprint for the cartridge. This is (wisely) done to help ensure that any and all factory ammo will chamber and fire, and also to help ensure general and all-around feeding reliability. Additionally, it’s common to find some (slightly) oval chambers in factory guns; that has a lot to do with the freshness of the tooling when that chamber was cut. It’s even more common to find them that are off-center.

Purpose-built bolt-action competition rifles, such as those constructed for use in NRA High Power Rifle competition, are custom-chambered* and, while few will use what we might call a “tight” chamber, it’s not likely to encounter one on the larger end of acceptable dimensions.
*”Custom,” here, doesn’t mean they are each unique, it just means that they are done by hand employing a precision-made reamer and therefore are what they ought to be, or we sure hope so. And they don’t tend to be overly generous in (any) dimensions.

neck sizing bushings
If you’re going to go, go all in: dies with interchangeable bushings let you control case neck diameter, adding another measure of control, and even less working and re-working of the brass.

So, in the circumstance where we have a chamber that’s a tad amount big and a cartridge case that’s been manufactured to (usually) the smaller end of SAAMI-set standards, that case will endure more expansion, in all directions, than if it had been in a tighter chamber. Sizing only the case neck to accept and retain another bullet, as said, reduces the subsequent expansion that will occur the next firing, but also, and this is likely if there is an accuracy improvement, the otherwise un-sized case might then be sitting more centered in the chamber. And one reason for that is, if the rifle is equipped with a plunger-style ejector (Remington 700 style) that will bear against one edge of the head of the chambered round, pushing the cartridge off-center, askew. (This ultimately creates another undesirable condition, a warp in the case, and we’ll talk about that another time.)

So, a little bigger case returning to a little bigger chamber likely has a little better chance of getting centered, and I truly believe that is why neck-only sizing can be a help to accuracy for a bolt-action. However! A dimensionally-correct case returning to a dimensionally-correct chamber will perform just as well on target. Full-length sizing a case for reuse in a rifle with what I call a “standard” chamber (which is really running a little closer to the minimums established by SAAMI) also makes for good groups. We prove that every High Power Rifle tournament.

Advice: If you notice your bolt-action doesn’t shoot too well with factory loads, neck-only sizing should pay off and is well worth a try. Do, however, make sure to gauge the cases as is often discussed in Reloaders Corner, and, specifically, cartridge case headspace. If the bolt isn’t closing easily, that’s liable to be the culprit right there: shoulder has gotten too tall.

If you’re running a factory bolt-action, by all means try neck-only sizing. If you want to compare results to full-length sizing, just make sure you’re doing that operation right.

david tubb
Now. Don’t go getting the idea that full-length sizing can’t shoot well. Here’s a 1000-yard prone group at the hands of David Tubb, originator of the 6XC cartridge. Tubb sets case shoulders back 0.002 inches, runs 0.004 case neck tension, and full-length resizes using what amounts to a “small-base” die (additional 0.0005-inch reduction at the case head). He’s also not shooting a factory chamber. (Photo note: the yellow pasters were sighters; red pasters indicate record shots).

Check HERE and HERE to get started…

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

RELOADERS CORNER: Cartridge Case Headspace

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Knowing, and controlling, this dimension is a crucially important step in the case sizing operation, especially for semi-autos. Here’s what it is and why it matters. Read all about it!

Glen Zediker

Last time, and to start the new year off, I hit a few highlights on the first of what I think are some of the most important things to understand in reloading for bolt-action and semi-automatic rifles. A majority of those differences is in what’s allowable and possible in cartridge case sizing.

The reason I’m running these articles is to clearly define the differences in, essentially, what you can get away with (and can’t get away without) depending on the action type. Don’t confuse some of the tactics, tools, and techniques used for bolt-actions and (mis)apply them to semis. That can range from frustrating (function issues) to disastrous (blowed-up guns). I hope that these focused articles will clarify the basics before moving on to the finer points respecting each.

case headspace illustration
Here’s headspace: it’s a height based on a diameter. A .223 Rem. uses a 0.330-inch-diameter datum; the height to the diameter on the case shoulder that equals 0.330 inches is the headspace dimension, measured from the case base (this is measured from the bolt face to determine headspace in a rifle chamber). There are only 5 datums that apply to all standard bottleneck cartridges; the correct number for your cartridge will be referenced in the cartridge specifications. (Belted magnums and rimmed cartridges are different stories, for a different story.)

Following on that, here’s one: cartridge case headspace. A rifle chamber has a headspace; a cartridge case has a headspace. The second cannot exceed the first. Here’s how it goes:

The area in point is the case shoulder, the area between the bottom of the case neck cylinder and the case body. There are two dimensions associated with case headspace: the diameter of the “datum” line, and the height (measured from the case base) to that line. So, headspace is determined by the location of the datum line. There are only 5 datum diameters in use over the range of bottleneck rifle cartridges. Datum diameter will be indicated in the cartridge description in any good loading manual. (Belted magnums, which headspace off the belt, are the exception, and different stories, and so are rimmed cases.)

Chamber headspace is determined by the chamber reamer and also the one operating the reamer. There are SAAMI standards for all standard cartridges (which are coincidentally those having SAAMI specs). Ammo manufacturers set their cartridge case dimensions to work within those same specs, and almost always with (literally) some room for variations. That means that, usually (and, again, I’m talking about factory-chambered rifles) the cartridge case headspace will be a little shorter than the rifle chamber will accommodate.

When a round fires, as is by now well-known, the case expands in all directions under pressure, swelling and conforming to the chamber, then retracts immediately afterward when pressure dissipates. Since brass has a plastic property, dimensions are not going to return to exactly what they were prior to firing, and that’s what all the sizing tools and operations seek to rectify. So, among other changes, the case shoulder will have “blown forward,” after having snugged up into that area of the rifle chamber. That will have moved the datum line upward. As hit upon last article, semi-automatics are notorious for exhibiting a little more than they “should have” in expanding, and that’s because there’s a little (to a lot) of pressure latent in the case when the bolt starts to unlock and move rearward. This can effectively create additional space for case expansion within the chamber. The case shoulder measurement after firing in a semi-auto might actually exceed that of the actual chamber headspace, or, at the least, be a little taller than it would have been in a bolt-gun having the exact same chamber dimensions. The hotter the load, the more gas system pressure, the more this might show.

case headspace tools
Get a few de-primed once-fired cases and a gage and get to work. Here’s a Forster Datum Dial gage. Works well and works for all standard-architecture bottleneck cartridges, as does the Hornady LNL. Each or either gives a “real” headspace number (although it’s not perfectly congruent, without mathematical manipulation, to the figure from a headspace gage used for chambering; that doesn’t matter though: as long as the gage is zeroed it shows the difference, and that’s what matters). By the way, the old standard “drop-in” style case gages might keep ammo safe, but won’t provide this sort of detail in information. The numbers we need to get from our gage are these: new, unfired case shoulder height (where we started); fired, unslzed case shoulder height (where we went to); sized case shoulder height (where we need to get back to).

To be rechambered, this case has to have its case shoulder “set back,” which means that the sizing die has to contact the shoulder area enough to budge it, bump it, down to a tolerable height. Here next is how to find out what that “tolerable” height is.

The process of adjusting a sizing die to produce correct cartridge case headspace is plenty simple and easy, and requires a specialty tool (and you knew that was coming): a gage to determine datum line height.

CHECK OUT MIDSOUTH Selections HERE

First, and important: this has to be done on the first firing of a new case, either a factory-loaded round or your own creation. For more conclusive accuracy, measure 4-6 cases, and, very important: de-prime a case before taking a read (the primer might interfere).

Measure a new case. Write that down.
Measure your fired case. Write that down.

Again, in a semi-auto the chamber might not actually be as long as the fired case reading says it is. In a bolt-gun, the post-firing case headspace dimension is going to be a closely-accurate indicator of the chamber headspace (but always subtract 0.001 inches from any reading to account for the predictable “spring back” in brass).

headspace reading
New — 1.458 inches.
headspace reading
Fired — 1.464 inches
headspace setting
Die setting — 1.460 inches.

To set the die, take the fired case reading and reduce it. How much set back? I recommend 0.003-0.004 inches for something like an AR15 or M1A. That’s playing it safe, considering, again (and again) that there may likely have been additional expansion beyond chamber dimensions. I’d like to see folks set back their bolt-guns at least 0.001, but I’m not going to argue! I don’t like running sticky bolts.

Set up case sizing die
Thread the sizing die down to touch the shellholder when the press ram is at its highest point of travel (whether it “cams” or not). Then back the die up (off) one full turn. Lightly seat the die body lock ring against the press top, and repeat the following process: lube and size the case, check the headspace; adjust the die downward, check the headspace. Rinse and repeat. For a 7/8-14 thread, which is virtually all presses, a full turn equals 0.0714 inches. That little nod of knowledge helps keep from going too far too soon, and also shows just how fine the adjustments get right at the end. When you think you got it, size a few more cases and read them. When you know you got it, lock the die ring. Note: the expander/decapping assembly was removed from this die, for one, because t doesn’t factor in establishing headspace, and because I set it all up separately on a new die. Headspace is the first thing I set.)

A little extra space ahead of the case shoulder helps ensure safe and reliable functioning in a semi-auto, and also, importantly, reduces the chance that the case might bottom out on the shoulder area in the chamber before the bolt is fully locked down. Firing residue in a semi-auto chamber is also effectively reducing chamber headspace, and that’s another reason for the little extra shoulder set-back. Keep the chamber clean!

headspace reading
Don’t just set the die bottom flush against the shellholder and commence to shucking cases! Most die makers provide that as instruction, and some say drop it down another quarter turn or so beyond that. That’s excessive. Here’s the read I got from flush die-shellholder contact on a new Forster.

Why not just set the shoulder back, for either action type, to what the factory set for the new case? Doing that really wouldn’t affect load performance, but, in my belief, deliberately creating what amounts to excessive headspace is not wise. It’s just that much more expansion, that much more “working” that the brass has to endure, that much shorter serviceable brass life. However! That’s not nearly as bad as leaving the shoulder too high! That’s dangerous.

NOTE: 
Bolt-Gun Only!
Do you have to do this with a bolt-gun? I say yes, but freely admit that, at the least, from zero to “just a tic” is safe enough. What you do need to do is know what you’re getting! For a bolt-action it is possible, and some think wise, to determine the necessary case shoulder set-back based on what is needed to close the bolt on the resized case: adjust the die down a tad at a time until the bolt closes. Depending on how stout the load is, it might be 2-4, or more, firings before the shoulder needs to be set back for a bolt-gun. But, rest assured, it eventually will. Just keep up with it. I think the bolt should close easily (and if you’re having issues with that in your handloads, there’s the first place to look for a cure). It’s really not possible to follow this plan with a semi-auto because the bolt will close with much greater force during actual firing. 

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

 

RELOADERS CORNER: Semi-Auto or Bolt-Action? Two Things To Remember

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There are essential differences in loading for these action-types. It might not matter if you know all about the one, but it is critically important to know about the other. Find out which is which… Keep reading!

casing in air
Any rifle with a gas operation system has to, well, have gas to operate! When it gets excessive is when the problems start. That’s another article, but the effects of the operating system is the basis for both the cautions in this article.

By Glen Zediker

Over the time I’ve been producing Reloaders Corner here at Midsouth, my focus has been exclusively on reloading for rifles, and, within that, primarily for semi-automatics. The reasons for that are based on two things, one is an assumption and the other is plain old fact. First, semi-autos are popular and represent the interest of a great number of new reloaders out there, and that’s my assumption. It doesn’t take long to come to the conclusion that high-capacity magazines and long days at the range combine to get expensive in a hurry! But the biggest reason I focus most of my material toward the needs of the semi-automatic rifle is because there are decidedly important differences in some decisions the handloader makes when tooling up for one. That’s the fact. Not knowing or respecting these differences can be disastrous.

I set out to be a sticker for clarity, but sometimes I overlook making more pointed references to these differences, when there are options associated with any one topic. I judge that based on the feedback I get from you all respecting tooling and component options. I want to start the New Year with this article, which I think contains some basic and important information to always (always) keep in mind. Hopefully it will also reduce questions, and I sure hope confusions. It also seemed to be, judging on feedback, the topic that created the most questions and comments.

Essential: When a round fires, the case expands, in all directions, as much as it can to fit the chamber. Since brass is elastic (can expand and contract) and plastic (can expand and retain that expansion) that last attribute, plasticity, results in a spent case that’s closer to rifle chamber dimensions than it was to its factory-new figures. Since many factory barrels have relatively generous chambers compared to most custom-done barrels, that’s either good or bad, depending on whether it’s a semi- or bolt-gun, and also depending (a lot) on what anyone buys into.

So, for reuse in a semi, that now overly-dimensioned case has to be brought back closer to nearer-to-new condition than it does for a bolt-gun. Has to be. Otherwise it might not chamber smoothly or fully.

full length sizing die
Due to the greater amount of case expasion, and also due to the need for smooth, easy feeding, any and every case used for a semi-auto should be full-length resized.

It’s important to understand that any semi-auto (at least any I’ve yet had experience with) has the cartridge case in a different condition right at the start of the extraction cycle. In a semi, the case is still holding pressure when the bolt starts to unlock. Bolt-gun, it’s all long gone by the time the knob gets lifted. That’s why a freshly spent case from a semi will raise a blister and one from a bolt-gun is cool to the touch. This pressure creates what amounts to greater case expansion in a semi-auto. Depending on the particular rifle and other factors that will get addressed in other articles, this varies from a little to a lot. The spent case measurements from one fired in a semi may not accurately reflect chamber dimensions, as they will with a bolt-gun.

The reason there’s still some pressure within the case when the bolt starts to unlock is because that’s how a gas-operation system functions. If all the pressure was gone the action wouldn’t even open.

neck only case sizing
A bolt-gun can be neck-only sized. I honestly don’t think this is a worthwhile practice, and I’ll talk more about that in another article, but as long as you’re willing to get a handle on case dimensions (so you know it’s still within specs to fit your chamber) it’s perfectly safe, and usually results in good group sizes.

Which brings us to the second essential difference in bolt- and semi-: Most semi-automatics, especially what is probably the most common (AR15 family) is very sensitive to gas port pressure. Gas port pressure is an actual measurement, but that’s not important to know, not really. What matters is understanding the effect of too much port pressure, and that is too much gas getting into the operating system, and getting in too quickly. That creates what most call an “over-function.” The action tries to operate, and the extraction cycle starts too early. There’s a lot of gas still binding the inflated case against the chamber walls. Many ills: excessive case expansion, excessive bolt carrier velocity, extraction failures (extractor either slips off or yanks the case rim, which can come off in a chunk).

.223 recommended components
Semi-autos are way on more sensitive about propellants, and, specifically, the propellant burning rate. Here is the set I use for my .223 Rem. competition loads (aside from a propellent that’s running in the range of the H4895, tough cases and thicker-skinned primers are part of the picture too).

From a reloading perspective, regulating gas port pressure is all in propellant selection. The burning rate range that’s suitable for semi-autos varies with the cartridge, but for both .308 Win. and .223 Rem. I cut it off at the Hodgdon Varget, Alliant RE-15 range: those are fine, but don’t go slower! Bolt guns don’t care about any of that.

RE15
Some will (certainly) disagree, but this is about the slowest-burning propellant I would suggest for .223 Rem. As a bonus, it’s also one of the highest-performing.

THE SHORT COURSE: Think “smaller” and “faster” when tooling up for sizing and choosing propellants for use (really, re-use) in a semi-auto. Smaller case sizing, faster-burning propellants.

This will all be hit on in upcoming articles in far greater detail but…

SEMI-AUTO: full-length case sizing, case shoulder set back at least 0.002 (from what a gage indicates as the fired case dimension), case neck “tension” at least 0.003 (difference between sized case neck outside dimension and loaded case neck outside dimension). Propellant selection: not too slow! Contrary to what logic might suggest, slower-burning propellants produce higher gas port pressures because they “peak” farther down the barrel.

BOLT-GUN: neck-only case sizing is (usually) okay (that means no case body sizing). Case shoulder set back: can be fine-tuned based on what’s necessary to easily close the bolt (ranges from none to “just a tad”). Propellant: doesn’t matter! As long, of course, as it’s suitable for use in that cartridge.

Check out some tools HERE at Midsouth

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.

RELOADERS CORNER: What Matters…

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Don’t lose sight of the basics when making tool, dimensional, or load choices. Here are four unchanging “musts” to make your results the best they can be. READ ON!

moly coated bullets
Bandwagon! I jumped on this one as did a whopping lot of others. Moly coating got a huge amount of attention and, indeed drastically improves bullet performance. The furf died down, though, after we discovered it had its share of problems (some were and some weren’t willing to accommodate or work around them). I still use coated bullets but now it’s Boron Nitride.

Glen Zediker

I have been basing some of my topics for this department on correspondence, and here’s another. Someone wrote asking me for a compare/contrast on the two handloading-specific books I’ve written, and the essential question revolved around whether or not the older of the two had been “updated.” Concerns were over inclusion or exclusion of new tools and propellants, and other components, and reloading techniques: essentially whether the newer book was better just because it was newer. Hmm… I thought long and hard about all that.

My answer, strongly self-paraphrased, was that there were always going to be new tools and propellants and bullets and cartridges and primers, but “what matters” in learning how to make ammo gin (accurately and safely) hasn’t really changed. Those who know my work over the past twenty-something years know I’ve never been eager to step up on a soapbox and proclaim coronation of the latest-greatest propellant, bullet, or even cartridge king. Instead, I’ve done my best to help folks learn how to judge merits and values of new things, based on a thorough understanding of all the old things. But this isn’t about me and it’s not just shameless self-promotion. It’s an overview of what I really think matters: it’s an effort to put into perspective the potential merits of all the new things.

full length sizing die

case neck sizing
Choosing the appropriate case and neck sizing die, and then learning how to correctly adjust it, for the needs at hand, which really means for the rifle the ammo will be used in, is another essential element in good loading.

For me, the four most important things to achieve with a handload are, one, that the case has been sized correctly and appropriately for the rifle; two, that care has been taken to ensure that the round is concentric (more in a bit); three, exercising some discretion in bullet velocity (also more in a bit); and, four, taking steps from reloading to reloading to maintain consistent performance.

Then there is an almost never-ending slew of finer points within all these points. And one ton of tools.

What I “know” about a load combination hasn’t come from one afternoon at the range. It’s often come from years. I have seen a whopping lot of bandwagons competitive shooters have jumped onto and off of. Newly hitched wagons are still rolling strong, departing continually. It is very important to have a set of components and processes and load structures to fall back on, which really then means a set that you can move forward from.

concentricity fixture
One of the “big four” goals I set for handloads is concentricity, run-out. Most of the tool and die upgrades I ever suggest making, as well as many case-preparation steps, seek to improve the straightness and centeredness of a loaded round. “Start in the center, finish in the center.”

I look at new things from a perspective of how and how well I can apply one of them to satisfy the same old needs. These needs are a filter, more or less, that helps determine if the new things are indeed improvements, or just new.

I am a competitive person. Our club CRO, Col. Floyd, once announced to the crowd at a local High Power Rifle tournament that I could smell gold-plated plastic through four feet of reinforced concrete… I admit to the truth in that. So, I am in no way suggesting that new things aren’t good, that we should all stay only with what we know. I’m always looking for ways to do better; but for me it’s not been so much trying something new, but rather taking another step using what’s been working pretty well for me thus far. That usually involves more focus on consistency.

I have a lot of stories about ultimate failures eventually resulting from initially wild successes, including lost championships, but the only value telling any of them would have is to make me sound way too old school. They are, again, never (ever) taken to mean that new things aren’t worth pursuit. Just shoot a lot of it under varied circumstances before packing it up along with the suitcase to attend a big event.

Back to setting down some tangible point to all this: most tool choices and case preparation steps I take have a goal of improving loaded round concentricity, which is to say centeredness or straightness. No doubt about it, a bullet looking dead center into a rifle bore is going to shoot better than one that’s cockeyed.

Cases with more consistent neck wall thicknesses, sizing die designs, and bullet seater designs can either enhance or detract from concentricity. Likewise, operations like outside case neck turning are done ultimately to improve concentricity. It matters!

The comment earlier about not getting too greedy for speed gets preached a lot by a good many, and the reason is avoiding anything that’s edgy. “Edgy,” to me, means something that’s going to take a turn for the worse on a day that’s 20-degrees warmer, or (in the case of the lost event mentioned earlier) 20-degrees colder.

pressure check carrtidge cases
Don’t get greedy on speed! An essential component in handloading success is consistency, predictability. Find a “tolerant” propellant, which means it demonstrates flexibility: shoots well at a little lower-than-maximum velocity, and shoots the same at different temperatures. No matter how small the groups were in testing, if pressure starts spiking due to some unaccounted for change those great test groups are likely to open up.

The best advice I can offer on this is, first and most obvious, use a little discretion working up a load to a ceiling higher than what equivalent-spec factory ammo can produce. It can take more than a few case and primer inspections to know if a “max” load is truly safe. Next is to get to work on finding a propellant/primer combination (mostly propellant) that’s showing good accuracy at less-than-max velocities. By that I mean I will not trust anything that seems to shoot well only when it’s running “hot.” Accuracy is, after all and always, what ultimately defines success.

(Since this piece is kind of a “year-end” thing, I plan to start the new year up fresh with a whopping lot more about specific new (and old) things that will help ensure you’re getting the most you can from your time spent at the loading bench.)

The information in this article is from Glen’s newest book, Top-Grade Ammo, available HERE at Midsouth. Also check HERE for more information about this and other publications from Zediker Publishing.