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RELOADERS CORNER: Cartridge Cases: The Outside, Part 1

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Lubrication is absolute essential in the reloading process, Here are a few ideas on which and how. READ MORE

lubing cases

Glen Zediker

What’s the most important thing in case resizing? Case lube! Overlook it or under-do it once and you’ll know why! A stuck-case remover is one of my very least favorite tools…

I have long used and recommended petroleum-based case lubes. More: I prefer those that are applied by hand, literally with the fingers, because I think it’s a better assurance that the right amount, to all the right places, will get laid down. I will quickly concede, though, that they are messy and slower than other methods.

imperial case lube
This is my favorite case lube. I took advice from Sgt. Norris after complaining how hard it was to get a good sizing pass on a Lake City .308. Sure enough. This made it easy. Been using it ever since. It’s not really wax. Use it like shoe polish: rub a little on your fingers and then rub it onto the case with a “gimme money” motion.

Spray-on-type lubes are very often used and recommended, especially by high-volume loaders because a good many cases can be treated and then even stored before use, so say the claims. I strongly suggest taking steps to prevent the lube from finding its way inside the case. A thin piece of cardboard placed atop the standing cases works well for this. There’s worry otherwise that the lube might affect the propellant. That does depend on the formulation, but I prefer the “no-chance” approach. I’m a “slow-down” sort of loader. That doesn’t mean I don’t want to save time or be as efficient as I can be, but I’ve just not found the speed advantage to spray-ons to overcome their performance. Sprays are not quite as “slick” as rub-ons.

Lanolin-based and wax-based alternatives also have their following. As do water-based lubes. The wax lubes indeed work and also clean up (off) easily, as does lanolin. I’ve not been a follower, though, because I find many to be more difficult to apply evenly and, one more time, just not quite as slick at petro-based products. Some of the wax-based lubes also make claim to “apply-now, use later.” I’m not sure what the appeal of that is, but there it is for those it appeals to. There are also a number of “proprietary” formulations out there now. I have not tried them all.

hornady case lube
Hornady pretty well has it covered: one for every opinion! Try them all! But I will wager you’ll like petro best… That’s the one in the bottle. Hornady claims their spray lube doesn’t contaminate powder, and that makes it applying it more straightforward.

A tip I picked up umpteen years ago by the man who got me started loading was to get an ink stamp pad (office-supply store variety) to apply roll-on type lubes. Indeed, that works way better than the industry pads I’ve tried.

Back to petroleum lubes: aside from providing smoother feel in sizing, which I have to believe also indicates “better” lubrication qualities, these don’t build up as much within tooling. I take apart my sizing die every now and again and swab it out, like I would a rifle chamber.

For best results, no matter which lube type you’re using, an even (thin) coating gives best results. With a good petro lube, it doesn’t take much. If you see any denting (usually in the case shoulder area), that resulted from hydraulic pressure and is a sign there was too much lube (too thick a coat). No worries, though: shoot the case and they’ll iron back out. Just use less lube next time!

Lubing the case neck inside is debated, but I favor it. However! Only very sparingly! That is why I really like the finger-applied lubes: just a little “wipe” across the case mouth eliminates the “gaunch” noice from the expander. I don’t use the graphite-applicators (the bin-and-brush types) because I haven’t noticed a whopping lot of difference in neck sizing with or without it.

forster lube
For best sizing results, I prefer the “rub-on” lubes. This one is from Forster. Never any worries about too much, too little, or complete coverage.

And, by the way, lube a case each pass through the die. This is important when setting up a sizing die where you might make a few passes with the same case. Don’t risk it! Stuck cases are total mood killer.

Clean the lube off the cases! There will be some now who will just roll their eyes, but I use denatured alcohol and a bath towel pour some on the towel, but the cases on the towel, fold the towel over the cases, and roll them around. Fast and simple! That works for petro-based. Others need more attention: just rub it away, or use detergent.

I do not recommend using a tumbler-type cleaner on loaded ammo!

Sho, there is a (slight) chance that a bullet tip might detonate a primer, but that’s not why. Why is because the propellant gets pulverized, and that, no doubt, will change its burn characteristic.

case cleanup
This is what I use to clean loaded rounds, along with the towel it’s sitting on. Lay out the towel, put down the rounds, pour some alcohol, fold the towel over the cases, and roll them around. Then hang the towel to dry for another use. Zero residue.

The reason to clean off the lube is because it lubricates, and that’s a bad thing on a live round. The case is supposed to stick tightly to the chamber when it expands under pressure. Any slip increases bolt thrust. I once saw a fellow douse a loaded 30-round magazineright down the middle with WD-40, to “make sure the bullets fed…” NO NO NO. Oil on a cartridge doubles bolt thrust!

Case lube is not a case cleaner!

Make sure the cases are clean prior to sizing. They don’t have to gleam, just be free from dirt and gritty dust. If you’re seeing a applicator pad, for instance, getting a dirty spot on it, well there’s your clue.

We’ll talk about that next time.

 Check out the selection from Midsouth HERE

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

RELOADERS CORNER: Primer Tech

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It may be the single-most influential reloading component, so learn all about it: the primer! READ MORE

rifle primer

Glen Zediker

This is one component in the collection that might not get all the attention it warrants. That’s because it is the one thing, above all other components, that you don’t want to just swap and switch around.

We’ve all heard cautions about testing new lots of every component, especially propellant, but primers not only change lot to lot, they vary greatly in their influence on any one load, brand to brand. The difference in one brand to the next can equal a good deal more or less pressure, for instance. While there are “general” tendencies respecting the “power” of various-brand primers, always (always) reduce the load (propellant quantity) when switching primers.

This has become more of an issue over the past few years as we’ve faced component shortages. I can tell you without a doubt that going from a WW to a CCI, or from a Remington to a Federal, can have a major influence on a load. I establish that from chronograph readings. No doubt, it’s best to have a good supply of one primer brand and lot that produces good results, and when that’s not possible, it’s a hard sell to convince someone to stop loading ammo and get back to testing. But. It is important. I can tell you that from (bad) experience. How I, and we all, learn most things…

When I switch primers, whether as a test or a necessity, I reduce my load ONE FULL GRAIN. There can be that much effect.

The Thing Itself
A primer is made up of a brass cup filled with explosive compound (lead styphate). Lead styphate detonates on impact. Primers don’t burn – they explode! In the manufacturing process, this compound starts as a liquid. After it’s laid into the cup, and while it’s still wet, a triangular piece or metal (the “anvil”) is set in. When the cup surface is struck by the firing pin, the center collapses, squeezing the explosive compound between the interior of the cup and the anvil. That ignites the compound and sends a flame through the case flash hole, which in turn lights up the propellant.

Primers are dangerous!

Don’t underestimate that. I’ve had one experience that fortunately only created a huge start, but I know others who have had bigger more startling mishaps. These (almost always) come from primer reservoirs, like fill-tubes. Pay close attention when charging up a tube and make sure all the primers are facing the right way, and that you’re not trying to put in “one more” when it’s full! That’s when “it” usually happens. What will happen, by the way, is akin to a small grenade. Static electricity has also been blamed, so keep that in mind.

primer tray
Take care in filling primer tubes! Make double-sure all are facing correctly, and a good primer tray helps. This photo shows the correct orientation for using primers one at a time. To fill a primer tube, make sure the “shiny side” is facing up! Flip the tray over.

Sizes and Types
Primers come in two sizes and four types. “Large” and “small”: for example, .223 Rem. takes small, .308 Win. takes large. Then there are pistol and rifle in each size.

Rifle primers and pistol primers are not the same, even though they share common diameters! Rifle primers should have a tougher cup, and, usually, a hotter flash. Never swap rifle for pistol. Now, some practical-style competitive pistol shooters using their very high-pressure loads (like .38 Super Comp) sometimes substitute rifle primers because they’ll “handle” more pressure, but they’ve also tricked up striker power. That’s a specialized need.

Further, some primer brands are available with a “magnum” option. Some aren’t. My experience has been that depends on the “level” of their standard primer. A magnum primer, as you might guess, has a more intense, stouter flash that travels more “deeply” to ignite the larger and more dense powder column. It reaches further, faster.

large rifle primers

large rifle magnum primers

There’s no real reason not to experiment with “hotter” and “colder” primers, whether the case is stamped “mag” or not. Keep in mind that the experiment is all about the initial flash effect. And keep in mind that this (without a doubt) demands a reduction in the propellant charge at the start.

Over a many years I’ve seen some tendencies respecting flash effect. Using routine cartridges, like .308 Win., single-base extruded propellants tend to shoot well with a cooler spark to start, and the double-base, especially spherical-types, seem to respond best to a hotter flash. Many seem to think that the coating (necessary to form the spherical) and the inherent greater density (less air space between granules) in a spherical demands a little faster start.

Flash consistency is very important, shot to shot. The consistency of every component is important: bullet weights, diameters, case wall thicknesses, and all the way down the list. We’re hoping to get more consistent behavior from a “match” or “benchrest” primer, and we’re paying more for it. I can tell you that some brands that aren’t touted as “match” are already consistent. That all comes from experience: try different primers, just respect the need to initially reduce the load each test. I can also tell you that my notes tell me that the primer has a whopping lot to do with how high or low my velocity deviations plot out.

One last: there are small variations in primer dimensions (heights, diameters) among various brands. These variations are not influential to performance. But! Small diameter variations can influence feeding through priming tools. This can be a hitch especially in some progressive loading machines. Manufacturers usually offer insight (aka: “warnings”) as to which are or aren’t compatible, so find out.

Check out Midsouth products HERE
Primer trays HERE

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

RELOADERS CORNER: 4 (More) Semi-Auto Details

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Beyond precision and accuracy, the base goal for any handload is safety: follow these recommendations to ensure yours! KEEP READING

Glen Zediker

Since I sincerely think it’s important to know what you’re up against, in one way of looking at it, when you load for a semi-automatic rifle, there’s more this time. I don’t mean to say “up against” like it’s some sort of adversarial relationship, a fight, but not respecting some of these points can create problems.

The gas port pressure issue was addressed last time, and it’s one of the most influential. Not only does too much port pressure create excessive action cycling, it also shortens case life. The cases take a bigger beating, more expansion mostly, when the bolt tries to unlock too quickly. Clearly, I’m back to using the AR15 as the central example, but virtually all semis succumb to the same set of behaviors (yes, including the gas-piston guns).

nosler brass
My current choice in a go-to for my “better” AR15 brass is Nosler. It’s not exactly thin but it is tough, and, by my experience, holds up to my standard. It’s also ready to load (well prepped).

One: tough brass
Therefore, next on the list is choosing a tough case! Tough, here, means “hard.” Brass is an alloy and the makeup varies from maker to maker.

The reason that a harder composition helps is because it’s more resistant to expansion, not as elastic. That might sound, on the front end, like a bad thing because harder brass is also more brittle so could tend to succumb easier to the ills of excessive expansion. Softer brass will conform more agreeably. True. It might seem like an equitable trade off, but I assure you that it is hardness ultimately that matters most. I notice the softness mostly in primer pocket expansion, or I should say that harder cases don’t open up as quickly.

Thicker cases, by the way, are not necessarily harder. Again, that’s in the alloy composition itself. Some high-dollar cases, Lapua for instance, are relatively soft despite being thick-walled.

The overall best choice for reuse in a semi-auto is probably good old Lake City. It’s exactly what it should be, and that’s been pretty well proven for decades. LC is easily available but, except in rare circumstances, will be once-fired. Most cases left over from commercially-available NATO-spec loadings are likewise fine. Lake City, as a bonus, also tends to be relatively thinner-walled (higher capacity) than many of the commercial brands, and its quality (wall thickness) is pretty dang good.

Check out what Midsouth has HERE

 

Two: adequate case shoulder set-back
Next, and this is a huge source of debate and disagreement amongst my readers, but, since now I’m strictly speaking of semi-auto needs I doubt there will be much dissent: full-length resize all cases! It’s a matter of degrees, and getting handle on port pressure (plus) taming down an excessively functioning gas system, reduces this difference: but most cases from most semi-autos will emerge with a pretty well-blown case shoulder. Make double-sure you’re sizing the cases down to at least 0.003 clearance. There are gages that help, and HERE is a link to one.

If you don’t there are safety and function problems ahead.

Three: adequate case neck “tension”
Likewise, make double-sure the case neck is being reduced an adequate amount to retain the bullet. There should be a minimum net difference of 0.003 inches between sized outside case neck diameter and loaded round outside case neck diameter. Reason: don’t take a chance of inadvertent bullet movement during the recoil and feeding cycles. That movement can be back or forward! It’s easily possible for a bullet to jump ahead when the inertia from the bolt carrier assembly chambers the next round.

sized case neck
Same as said about headspace: a bolt-action can “get away” with a lot, but a semi-auto round has to be constructed with an eye on cycling stresses. A firmly-held bullet resists stubs and intertia-induced movement. I recommend a minimum of 0.003 “grip.”

Four: tough primer!
Choose a tough primer! There’s a floating firing pin on an AR15 (M1A also) that is supposed to be held in check but that system doesn’t always work! If you load and extract a round and see a little dimple in the primer, that’s from the firing pin tapping off of it (again, created by inertia of bolt closing). A combination of a high primer and a sensitive primer cup assembly can create a “slam-fire,” which you do not want.

primer indentation
This always scares me. A tough-skinned primer is a very wise choice loading for anything with a floating firing pin, like an AR15 or AR10.
No! Check each and every primer to make sure it’s seated to below flush with the case head!

Brands? CCI has some mil-spec primers that work well, and I’ve had great success with Remington 7-1/2. Some of the well-respected “match” primers are a little thin. The CCI and Remington also hold up well to the (sometimes) greater firing forces working on the primer (again, from the quick unlocking).

And, finally, make double-sure that each and every primer is seated to below flush with the case head! That’s true for any firearm (because it also means that the primer is fully seated) but imperative for safety in a semi-auto. This is especially an issue for those who use a progressive-type loading press. There’s nothing wrong with the press but it may not give the sensitivity in feedback to know that the primer is fully seated without checking.

Here’s what I use from Midsouth

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

RELOADERS CORNER: Blissful Moderation

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Glen Zediker recollects and reflects on the first advice he ever got on choosing a load: all things in moderation, pressure and velocity included! READ IT ALL

range load
When you just want to load up and go have a go at the range, there’s no need for speed. But! There is a need for enough pressure-power for reliable, clean function. I suggest trying something in the “medium” range for daily use. Your rifle, your barrel, your cases, and your senses will all thank you for reducing the shock by taking “two steps to the left” to find a load. Promise: you will not notice anything at all negative from any lack of “power.”

Glen Zediker

I spend a great amount of space in this department warning, and I hope educating, on the signs, signals, dangers of excessive cartridge pressure. That’s all been and being done because, for the majority, maximizing velocity is an ammo-goal. Hunters, varmint and game, competitive longer-range shooters, usually want the most they can get from bullet flight performance, and also impact strength.

For me, there’s zero doubt that more speed is a better score on a full-length NRA High Power Rifle course. (Side note: it is a fallacy that lighter loads are more accurate. They’re not, or not because they’re lighter. Some of the best perforations I’ve seen are with maxed loads.)

But! I shoot a toned-down load for reduced-distance courses (as well as for the 200-yard events on full-length), and my general-purpose clods-and-cans load is a lower-stress recipe.

I mentioned last time that I had recently fired a good deal of current NATO-spec ammo and was, I guess “impressed” is the right word, with its power level. The stuff I make up for afternoon fun-runs is a good deal less stressed.

I’m not at all recommending a “light” load. Just let’s call it a solid “medium.” Looking over my notes for the past umpteen years, going through my last most current load-data notebook, I saw what was to me an interesting happenstance. I tended to be pretty much right at one-and-one-half grain less than maximum (and about two grains with .308-class rounds).

dirty case
Signs of a load that’s too “light” include, clearly, one that won’t cycle the action reliably on a semi-auto. Another couple, for any action type, include an unusually dirty chamber and sooted-up cartridge case necks and shoulders. A little lighter still and you might see a primer that’s backed out a tad. Those all result from the case not expanding fully to seal the chamber forward and stretch to comply closer to chamber dimensions end to end. A little reduction won’t normally show any of this, and, tip: go a tad toward the faster end of suitable burning rate for general use.

Thats not a light load! It’s “three halves,” three one-half grain drops. That half-grain, and some might recollect my mentioning this a few times in the past, is my always-recommended “come-off” step for any pressure sign (not a tenth or two, but a “full” half grain). Any other over-pressure indicator from that point then signals need to come off another “full” half-grain. So I pretty much come off those two halves from the get go, add another, and, guess what? Never nary a pressure concern.

Slightly faster-burning propellants, in my experience, lend themselves better to the “medium” power level reduction in terms of maintaining accuracy. As always, “faster” and “slower” are values within a small range of propellant rates suitable for a particular cartridge and bullet. And, in following this plan, when needed bump it up to full speed with predicatable results.

For .223 Rem.-class cartridges, a half-grain is worth ballpark 40-50 feet per second, again depending on propellant.

The advantages of a “medium” load are predictable, but here’s my list: plain old easier on the gun, and on the barrel, and on the self. Again (and again) I’m not talking abut a “light” load, just one that’s maybe 95-percent, a solid 150-200 feet per second less than published maximum. Case stress will be reduced, and that’s associated with length trimming frequency and overall “life” before primer pocket enlargement and general stretch-thinning, cracking symptoms retire the brass.

Back to my “story,” which was the interesting happenstance (all this was all brought back to me by the initial outing with my new old AR15 I talked about last edition, and my 16-year-old son asking me if I could teach him how to reload because we ran out of ammo so quickly…): So. When I first learned to reload I was 15. This event coincided with my first AR15 rifle, which was purchased new at a Skaggs drugstore. Right. My mother did not eagerly agree to sponsor a reloading setup, but, being a wise-enough woman, did interpret the math the same way I did: I could shoot a lot more for a lot less if I was doing my own. So, I had a friend, Gary. Most fortunate man to know. Gary, and I see this more clearly each year that passes, knew more about guns and shooting than any 10 people I have since encountered.

We went to Bald Bob’s Sporting Goods in Rifle, Colorado. He chose an RCBS kit for me, a piece at a time. Bob sold RCBS only. Press, dies, scale, meter, case lube, doo-dads, and, of course some propellant and brass and bullets and primers. And a Sierra Bullets loading book. So, back home, and a short time later, there I sat before my new array of green pride-and-joys. After stern lectures about things I was never supposed to do, and at least an equal number of things I was always supposed to do, we got this show flowing downriver.

Gary had chosen IMR 4198 for me for a propellant. He said it was clean-burning and economical. Didn’t take much of it. I had some Speer 55-grain full-metal-jacket bullets, some Remington cases to go along with the empties I had saved in a paper bag, and some CCI primers. Now. We looked at the loading tables in the Sierra Manual, and he had me find my cartridge and bullet. (He already knew exactly where we were going, so this was for my benefit.) He pointed out the “maximum” load and the “starting” load, one on the far right and the other on the origin point of the table on the left. He then counted back two places from the far right: 20.5gr. He said, “There. That’s the one. It’s not going to give you any troubles, and it’s adequate for function.”

“That was easy,” I thought.

I have since learned that advice was too good not to share.

If you’re looking for a good load, and you know the propellant is wisely-chosen, going two steps down from the manual-listed maximum should, indeed, be a great place to start, or to stay if you are sans chronograph. Time after time, I have noticed over the many, many years I have now been doing all this, that the “two steps back from max” procedure is safe, sane, and satisfying.

reduced load list
Here’s a page (“the page”) from my now-ancient Sierra manual. Not all manuals agree (not nearly) on max loads, and not all are done in multiple increments, but the essential advice is reducing the max load by two steps, or about one-and-one-half grains of propellant in this case (reduction amounts vary, certainly, based on the cartridge). It’s wise advice from a wise man, and I’m talking about Buddy Gary. I just pass it along because it sho works for me!

I shot about a gozillion rounds of 20.5 grains of 4198 through that SP1. Since it was not a max load, I could also change the bullets without worry, going from one brand to the next at the same weight, of course. I could change cases and even primers. It was a tenth shy of one-and-one-half grains under maximum. I don’t recollect ever grouping that rifle on a paper target. I zeroed it based on preference and I also don’t recollect ever missing anything I aimed at by more than a little bit, and never twice.

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

RELOADERS CORNER: 5.56 NATO: “GO,” “NO-GO”

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This “warning” has been around, and around, for years, but it’s still not always heeded, or understood. Read why and how it matters HERE.

nato stamp
The circle-cross stamp is a NATO-spec cartridge. Your barrel might be marked “5.56” or a more lengthy disclosure referencing its specs. If it’s “.223 Rem.” do not fire a NATO round through it! Your barrel might also not be marked at all. I’ve increasingly seen that. Get it checked. A NATO round will chamber perfectly in a .223 Rem. All exterior dimensions are patently the same, again, it’s the pressure level.

Glen Zediker

I know this is “Reloaders Corner,” but, every now and again at least, I rip open the end of a cardboard factory cartridge box, or five.

I just got finished building up a “retro” AR15 for a new book. Reasons for that are a few, but probably the main one was that I wanted to recollect the one that “got away,” well, the one that I let go. Errant short-sighted judgment, as is common in youthful people. So I built a replica M16A1, circa mid-60s, well, of course, with only two selector stops. At the heart of that rifle is an original-spec barrel, chrome-lined, NATO chamber.

5.56 stamp
This is a NATO chamber stamp. If it’s “.223 Rem.” that’s NOT the same!

That’s leading to this: I opened up a few boxes of “genuine” NATO 5.56 to check it out with, something I honestly haven’t fired for years and years. Dang. That stuff is potent. Over the past several years, the pressure level has increased. Current standard is a little over 62,000 PSI. (NATO is technically measured differently than commercial, but the figures I give here are accurate for comparison.) Compared to SAAMI specs for .223 Remington (commercial) that’s a solid 7,000 difference. (That SAAMI-spec figure has likewise increased over the years, judging from recent test figures I’ve seen respecting commercial .223 Rem.; most references heretofore were max at 52,000 PSI.)

The main impetus for this article, though, came from a recent experience at a local gun shop. I went in search of a sub-sonic .300 Blackout load, and they had one in .300 Whisper. The counter person told me that it was “exactly the same as .300 Blackout, just like .223 is the same as 5.56…” Whoa. Neither statement is true, although Whisper specs are plenty close enough to Blackout that no differences factor in safety or function. However! I didn’t take the time to lecture, but, dang, .223 Rem. and 5.56 NATO are not nearly the same.

First point: do not fire NATO-spec ammo in a rifle with a chamber marked “.223 Remington.” It will, not may, be over-pressure. Reasons have to do with chamber specifications for 5.56x45mm NATO and those for SAAMI-spec .223 Remington. There is a significant difference in the leade or “freebore” cut comparing SAAMI to NATO. That’s the space in a chamber ahead of the cartridge case neck area that leads into the rifling. NATO is radically more generous, meaning “bigger”: longer, more volume. (About 0.150 inches, based on my measurements of bullet seating depths that touch the lands.) There is relatively much more room for expanding gases to occupy in a NATO chamber. In a SAAMI chamber there’s much less room for expanding gases to occupy. The additional pressure is about the equivalent of another full grain (or more) of propellant in the case. Yikes.

high pressure nato
Here’s what happens putting a factory-fresh NATO round through a .223 Rem. chamber. This case is clearly beat. Sure, it might, should, hold up for that firing, but the case is done and the gun took a needless hammering.

nato beat case

There are other little nit differences to pick between the SAAMI and NATO cartridge, and, therefore, chambering specs, but they don’t really factor in a material sense. There’s bound also to be just as many small differences in cartridge dimensions from one maker to the next. I’ve measured enough to tell you that’s true.

Now. What this has to do with reloading (finally, I know) is based on a question I’ve gotten over the years, a concern to some, or at least, as said, a question. And the answer is that you’re better off going with .223 Remington loading data for any ammo intended for “general” range use. That means blasting away on an afternoon. Just because it’s a NATO chamber does in no way mean you’re supposed to run NATO-spec ammo through it! Back it off and enjoy it more.

If you’re relying on a factory-published data manual to give a place to start, or stop (something from Sierra, Hornady, Lyman, or so on) pay very close attention to the test barrel specifications. Clearly, barrel length has a big influence on attaining the published velocities, and some load combinations are going to be worked up using considerably longer barrels than what the most of us have on our AR15s. But the biggest factor is the chamber used in the test barrel. If it’s a SAAMI-spec (sometimes called a “SAAMI-minimum”) chamber then the data should be on the conservative side. Should be. Do not, however, bank on any idea that you should jump straight to the maximum load listed if you’re loading for use in a NATO. There are, always, too many factors that otherwise create more or less pressure (primers, cases, propellant lot, and more).

As time goes by it probably is less likely to encounter a semi-automatic “.223” that’s not a NATO, but it will be marked as such! Clearly, most ammo is used in the most popular guns. That’s not going to be a bolt-action anymore. Make no mistake, though, AR15s exist plentifully that have SAAMI chambers, and I see a lot of aftermarket barrels that are cut with that minimum-dimension reamer.

ANOTHER OPTION
So what’s a “Wylde” chamber? This is a chambering spec developed by Bill Wylde, one of the early and leading pioneers in the quest for improved AR15 accuracy. It is popular and available, especially in aftermarket barrels. What it is, is a chamber that’s in-between SAAMI-minimum and NATO, leaning closer to NATO. Rumors are true: it’s safe to fire NATO-spec factory loads through a Wylde. The Wylde was designed upon the introduction of the heavier competition bullets with the idea of providing more freebore to accommodate the necessarily longer cartridge overall lengths necessary with something like an 80gr. Sierra, but keep the amount of jump to a minimum with shorter bullets fed from the magazine.

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

RELOADERS CORNER: Why Not Flat-Base?

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A better question, given that the vast majority of popular rifle bullets are boat-tail, is why flat-base? KEEP READING

flat base bullet

Glen Zediker

Good question! I have something that at least has elements of an answer.

A boat-tail bullet is the standard for the majority of rifle bullets, and the domineering choice of long-range shooters. Competitive Benchrest shooters favor flat-base bullets. Flat-base is also popular with varmint-hunters: the stellar Hornady V-Max line for good instance.

Hmm.

We all want best accuracy, so why the difference? Consider the overriding characteristic of a flat-base bullet: it’s shorter. Now, since not all flat-base bullets are shorter overall than a same-weight boat-tail (they’re usually not), I seriously need to clarify that!

Clarification: a flat-base can be shorter, and lighter, than it would be if the same ogive or nosecone profile used then added a boat-tail. More: if they’re both the same weight and at least similar in profiles, a flat-base often has a longer bearing area than a boat-tail bullet, again because the boat-tail is sticking down there, or not. These are both a bonus to Benchrest or any other shorter-distance circumstance where utmost precision is the goal. (When I refer to capital-b “Benchrest,” I’m not talking about a shooting rest, but a competitive sport.) Shorter bullets allow slower barrel twists (bullet length, not weight, chiefly governs needed twist). Slower twists offer a miniscule improvement in damping a bullet’s orbital pattern in flight, and considering the likewise near-caliber-size 5-shot groups these folks are after, that matters. Bullets fly in a spiral, like a well-thrown football. Again comparing those with similar profiles, flat-base bullets stabilize faster and sooner than boat-tails, it’s a smaller spiral. Bullets with longer bearing areas tend to shoot better “easier,” less finicky. And, flat-base bullets can provide more cartridge case capacity.

vld and ld compare
Here’s unique. Jimmy Knox of the original JLK Bullets once made flat-base versions of his Davis-designed VLD (very low drag) boat-tails. So this is a .224-caliber flat-base 65gr LD (low drag), which is the same as his 80gr VLD shown with it, just no boat-tail. Why? It was more of a “Why not?” Idea was to provide better downrange performance for those with slower-twist-rate barrels, and to retain the flight pattern and in-barrel characteristics he liked about flat-base (and way on more speed). This idea was popular among some better High Power shooters about 15 years ago.

All those good points make it sound like flat-base provide superior accuracy. They might. By my experience, they do, but! Distance defines the limit of that truth.

The boat-tail provides an aerodynamic advantage, and the farther it flies, the greater this advantage. There are well-founded beliefs that boat-tails are less influenced by gas pressure thrusting against the bullet base. A good and most knowledgeable friend at Sierra told me that a boat-tail has an effectively more concentric radius at the base due to the junction point created by the angle on the tail and the bearing surface. Further, a flat-base, is, in effect, harder to make so that the base will have a radius that’s as concentric with the bullet bearing surface. Manufacture care and quality (related), of course, makes that more or less true or false. If the idea is that a good boat-tail is “easier” to make, that this shape makes the end product more forgiving of manufacturing errors, then I’ll accept that since it’s pretty hard to argue against, but, again, I really don’t think that boat-tail designs simply take up slack in quality tolerances. I’m sho no rocket-surgeon but I know that the tail slips the air better.

LD_ and Hornady 68
Same LD bullet compared to a Hornady 68gr HPBT. The 65 is a tic shorter overall but, because it’s a 15-caliber (!) ogive, way less bearing area (exception to the “rule” big-time) than the boat-tail next to it. The 65 had a higher BC but was über-tricky to get to shoot well. I could get these to just over 3000 fps in a 20-inch .223 Rem. Mostly because of the tiny bearing area.

This can get pounded completely into the ground because adding a boat-tail (and I’ll show a great example of just that) to a similar nosecone also adds weight to the bullet, and that increases BC. It’s not exactly a chicken-egg question, though, because the tail helps otherwise.

barts bullet
Here’s a 52gr boat-tail from Hornady (right) next to a 52gr custom Benchrest bullet. I said the overriding difference is that a flat-base bullet is shorter, but that’s not referring to overall length. A flat-base is shorter than it would be as a boat-tail, if the other dimensions were the same, and usually has a longer bearing area.

You might have also heard said that boat-tails shorten barrel life because the angled base directs burning propellant gases more strongly at the barrel surface. They do, and many steadfastly uphold that as a reason against them. More in a bit. However! Beyond 300 yards, at the nearest, there are no disadvantages in using boat-tail bullets that come close to surpassing their advantages.

There’s another debated advantage of a flat-base and that is they tend to shoot a little better in a barrel that’s about to go “out.” I’m talking about a good barrel that’s pushed the limit of its throat. That one is true too!

And speaking of barrel life, another is that flat-base bullets produce less flame-cutting effect than boat-tails. A barrel lasts longer if fed flat-base. True! Flat-base bullets “obturate” more quickly. Obturate means to “block,” but here it means to close a hole, which is a barrel bore, which means to seal it. The angled boat-tail creates a sort of “nozzle” effect. Can’t much be done about that, though, because when we need boat-tails we need them. That is, however, a big score of help for the varmint hunter.

There is a relatively obscure “combo” out there called a “rebated” boat-tail. This has a 90-degree step in from the bullet shank (body) to the tail. It steps in before the boat-tail taper is formed (they look like a flat-base with a boat-tail from a bullet a couple of calibers smaller stuck on there). It’s common for competitive .308 NRA High Power Rifle shooters, for instance, to switch from the popular Sierra 190gr MatchKing to a Lapua 185 rebated boat-tail when accuracy starts to fall off due to throat wear. Sure enough, the Lapua brings it back for a couple hundred more rounds.

rebated boat tail
Here’s a rebated boat-tail. 115 grain 6mm from David Tubb.

If anybody with heavy equipment making bullets for sale out there is listening: I’d like to see some more rebated boat-tail designs! It is, though, a challenge to make precisely.

So. What? So what? Well, if you are big into small groups, I very encourage some experimentation with flat-base bullets. Again, distance is the only limit to their potential goodness. 100 yards, yes. 200 yards, yes. 300 yards, no!

vld chamfer
One thing is for certain: Flat-base bullets are not nearly as easily seated! Some have an edge-radius, some don’t, but, they are very easy get started crooked, or difficult to get started straight, same effect. I strongly recommend taking steps to square case mouths and use a generous chamfer.

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

RELOADERS CORNER: What I do…

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There are a lot of ideas and options when it comes to loading the “most important” ammo. Here’s the 5-step process I ended up with… READ MORE

dial indicator

Glen Zediker

I spend a lot of time telling everyone else what they should do, and probably more time telling them what not to do, or what they could do… I thought it might be best to tell you all exactly what it is that I do to prepare a batch of ammo for a tournament.

That’s a quick way to show you what, clearly and obviously, matters to me. I admit: I don’t always do all the things that I talk about. A big part of my role here is to pass along information, answer questions before they’re asked, in a way of looking at it. There’s information, and then there’s action, and that’s not a contradiction, to me. For instance, I can tell you all about case neck turning, and metplat uniforming, and many other preparation steps. I have done them all, sometimes do them, but dang sho not always.

Believe me: I have tried everything and much, much more than I’ve ever talked about in these paragraphs.

Following is what I have found works to my satisfaction. Since I’m dealing with a fair amount of cartridges at any one time, there is, no doubt, a time and effort element that’s important to me. In other words, what’s coming next are the things I really think I must do to give my score the best boost I can reasonably give it.

Step One: Get my cases together and size them. I load in 100-round batches, so I start with five boxes, or whatever corresponds to 100 rounds. Without so much as a second glance, I run them all through my full-length sizing die: lube each and cycle it through. If nothing else, most new cases are not nearly ready to load. The case necks are usually banged up, not round, so at the least I’d need to size the inside and outside of the case neck, and I’ve found that, while other appliances will suffice for that, it’s just easiest to use my sizing die.

Step Two: I trim them all. This isn’t done as any matter of safety, just consistency. I set my trimmer to at the least touch each case mouth. This is very important! The next prep steps rely on having cases that are all the same length.

case trimming

Step Three: After chamfering inside and outside (I use a 17-degree on the inside and a standard tool for the outside) I run a flash hole uniformer through each. This is why it’s important to have them all the same height. That way the uniforming tool cuts to a consistent depth.

inside uniformer
After full-length sizing all my new cases (to mostly get the necks shaped up), I trim all the cases to ensure length consistency to start, because the next procedure, inside flash hole deburring, demands it. Shown is from Hornady. CHECK IT OUT HERE

Step Four: Primer pocket uniforming. I run each through this process. Now, I have had some lots of brass that make this normally simple process a chore, and that’s because the reamer is too snug a fit to the pocket. We all know that primer pockets are at their smallest on new cases. That is, by the way, one reason I’ve mentioned that the primer pocket “feel” is a leading indicator after the first firing as to the pressure level of the load. In keeping, there are times when I wait until recycling the first-fired cases before running the uniformer. It depends on how readily the cases will accept the reamer.

primer pocket reamer
Primer pocket uniforming is an important step in my own process, but sometimes I wait until the first-firing. Depending on the tool used, and how much power can be applied to assist, this job can be a chore on a tight pocket. Shown is a Lyman tool. CHECK OUT TOOLS HERE

Note: I consider my “best” ammunition to be that which I load on my once-fired cases. At the same time, I won’t hesitate to use new cases for a tournament (but not for a Regional or bigger event). Over a whopping lot of time keeping notes, my “second-firing” rounds tend to shoot a tad better, but it’s a miniscule amount. That’s why I don’t really sweat over the primer pockets on the first go-around.

Step Five: Roll them all! I run all the cases through a concentricity fixture, aka: spinner, to check runout. I segregate on the following criteria: “flatliners” no visible runout, less than 0.001, 0.001, up to 0.0015, more than that… Five piles. One reason I do 100-round batches is because I need, technically, 88 rounds for a tournament. Since I am using “name-brand” brass, I easily find my 44 prone-event cases that are going to be no more than 0.001 out of round. The remainder are proportioned better to worse for the 200 yard events. It’s not that I don’t think each round matters, because it does, and, honestly, the 200-yard Standing event is what wins a tournament, but that’s way on more on me than the ammo. A case with 0.015 runout is not going to cause a “9.” That case will produce groups way inside the X-ring.

Co-Ax Case and Cartridge Inspector
I segregate using a runout indicator, a tool shown before in these pages. Some argue, logically, that the best way to find cases with the most consistent wall thicknesses is to measure wall thickness, but, my experience has shown that, ultimately, concentricity is the result of wall thickness consistency. Sho is faster. Shown is a Forster Co-Ax Case & Cartridge Inspector

Now. I fully realize that segregating by runout, concentricity (“centeredness”), is not the same as actually measuring case neck wall thicknesses. However! “Flat-liners” are what ultimately result from consistent case neck walls. Since I have also sized the inside of the case neck, not just the outside, the spinner does give an accurate indication of case neck wall consistency.

case segregation
After sorting by runout, here’s what I get, or what I got once… These were graded (left to right) 0.0000 (no perceptible runout), up to 0.0010, 0.0010, 0.0015, and more than that. So, here, there were 37 cases that were at or near the level of neck-turned cases, and another 37 showing only 0.001, but way on easier.

Since it’s often the night before that I’m doing this, spinning is way on faster than measuring…

Then I prime, fill, seat. Get some sleep.

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

RELOADERS CORNER: Meter Use Tips

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How well you set up and operate a powder meter has a lot to do with ammo consistency. Here are a few tips on getting the most from this tool. READ MORE

Glen Zediker

Going back to our last conversation, the topic was dispensing propellant charges, and whether to weigh each charge or dispense each charge using a powder meter. Generally, most seem to agree that weighing each is the sure way to better consistency. I don’t always agree with that, and I say that mostly because my chronograph and group size numbers don’t support superiority of either approach. However! I sure do know that metering charges is way on faster and easier than weighing them all out!

Once again: the only answer that works is to experiment for yourself and settle the question based on empirical evidence. Right: shoot it and see!

This next offers a few tips I’ve had good success with over the years. I can tell you that, without any doubt, learning how to set up and operate a meter has a decided influence on those chronograph and group size measurements.

scale weight
I am adamant about following this process to set a meter: Don’t throw and weigh single charges to adjust the meter. Throw and weigh 10-charge portions, with the scale set, of course, to 10-times the desired single-charge weight. I do not recollect one time when my meter adjustment did not change following this process from what I first arrived at weighing single throws. Here’s how I set it to adjust for a 24.0 grain throw.

First: I very strongly recommend setting the meter throw based not on one single charge, but on multiple charges. Here’s my method: After running a few single throws to get it close, I set my scale to 10 times the desired single-throw propellant charge weight, then throw 10 charges into the scale pan. I have done this (so) many times over (so) many years that I can tell you that I have no memory or record of this tactic not influencing the final setting I have dialed in. Do this 3-4 times and see what you see. There’s a huge likelihood there will be an adjustment needed. And for some reason, supported by my notes at least, the final setting is usually a tick lower than I gauge for one-throw-at-a-time weight checks.

Now, I know that if the meter is accurate then each single charge will weigh what it should, but maybe the difference that makes this method work best is that scales aren’t perfectly accurate. Maybe it’s the damping system, or continual issues with calibrations, but a 10-throw lot ultimately results in a more precise setting. I’ve proven that too many times to myself to qualify it with a “may.” No, it does.

As mentioned in a past article, the smaller the propellant granules the more precise each fill can be. Longer-grained kernels provide more air space and “stack” more than smaller-grained kernels. It’s also clear that the higher degree of precision on the meter internal sliding surfaces, the more “clean” the strike-off will be.

And, meter operation has a whopping lot to do with the consistency of filling the meter drum. Just like tapping a case bottom settles the propellant to a lower fill volume, same thing happens filling the drum in a meter.

powde meter operation
Not too heavy, not too light. Work the handle the same each time, and have it come to a positive stop. “Thunk. Thunk.” Focus on a consistent speed. This has a huge effect on how consistent the throws will be.

The trick to good throws is working the meter handle consistently, and also settling on a contact force when the meter handle comes to a stop in the “fill” direction: It should bump but not bang… I wish I could be more clear on that, but it’s a feel. Don’t go too slowly, gingerly taking the handle to its stop, and don’t slam it there either. You want a positive, audible “thunk” when the handle stops. If it’s the same each time, fill consistency will, not can, improve. Focusing on operating the handle at a constant rate of speed teaches this in short order. It’s a positive movement that, for me, takes about one second to lift the handle.

harrells meter
I recommend longer drop tubes (meter or funnel). The longer tube has the same effect as tapping the case to settle the propellant. This helps in loading stick propellant into small-capacity cases. Rubber-band a dryer sheet around the propellant container to static influence, which can be an influence, especially in the Western regions.

There’s a few more tips in the photo captions, and here’s another: Do not leave propellant in a meter! Return it to a sealed container when you’re done for the day.

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

 

RELOADERS CORNER: Throwed Vs. Weighed

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This is an age-old debate among precision reloaders, and here’s to hoping you can find your own answer. Here’s a few ideas on how…

Glen Zediker

Since we (well, I), have been on the topic of velocity consistencies, clearly, this next here factors mightily among points in this general topic. I would also very much appreciate feedback on your own experiences. This, therefore, isn’t so much me trying to convince anyone of anything, but rather an effort to give some credibility to “both sides” of this question. The question, as suggested by the article title: Are meter-dispensed propellant charges equal in performance to singly-weighed charges?

Most are going to own a powder meter. Technical tickiness (that’s actually important): such a device is a meter, not a “measure.” Meters don’t measure. It’s most accurately called a “dispenser.” That’s what it really does. The “measure” is comparing a meter drum volume to a weight on a scale. It’s a volume, not a weight. The volume corresponds to a weight that was arrived at through adjusting the meter volume.

And this kind of keeps going in circles: is it a weight or a volume, then, that matters? A good many chemistry-inclined folks have told me over a good many years that any and all chemical measures are always weight, never volume.

harrells
I think a truly good meter is necessary to provide reliable results, especially if you want to ignore weighing each charge and rely on thrown charges for your record rounds. There are good meters available, but this is one of the best: Harrell’s Precision. It uses the proven Culver-style mechanism. See one HERE

Now then there’s a question about adjusting volume for that weight. I don’t know if you’ve ever experimented with this, but I’ve weighed the “same” powder charge at different times and had different weights (storing it in a sealed film canister and weighing on different days). It’s not much, but it’s different. It pretty much has to be moisture content that’s changing the reading, and, most lab-standard dispensing recipes (such as used in pharmaceuticals) have a set of condition-standards that accompany compound weight. Compounding that, using some electronic scales, I’ve had to re-zero, more than once, in a loading session weighing out charges. I have an inherent suspicion of scales. Old-trusty beam scales with a magnetic damper can finish a little high or low due only to the magnetic device. There’s a certain amount of inertia the beam has to overcome. Tapping the beam a few times will show that, indeed, it can come to rest variously +/- 0.10 grains, or more.

I don’t have a definitive answer to this question!

I can safely say that “it depends,” and what it depends on is a long list. First, as suggested, is scale accuracy. I don’t know that it’s always all about money, but that, no doubt, is a leading contributor in product quality. As said, I become suspicious of any device that requires a re-set during one use-session. For myself, I have confidence in my meter, and that’s come from countless “quality checks” I’ve run over the past couple of decades. I’m not a mathematician, so perhaps those who are can tell me if my logic is flawed in making the next assumption, but I developed confidence in metering charges based on collectively weighing multiple charges. Like so: throw 10 into a scale pan, weigh it. Repeat, repeat, repeat, and make note of how much plus-minus there is in each try. Using the propellant I stick to for competition NRA High Power Rifle loads (Hodgdon 4895) I get never more than 0.2 grains variance for a 10-throw batch. I don’t know how many single throws might be more or less than that and maybe it’s pure luck that all unseen errors offset rather than compound, but I prefer, at least, to believe that means my meter throws pretty well.

reloading scale
A truly good scale is likewise important if you’re going to rely on weighing each charge. If not, then just about any scale is accurate enough to set a powder meter. Speed factors heavily in being happy with a constantly-used scale.
trickler
You’ll need one of these too! A powder trickler. It’s used to drop in one kernel at a time to perfect the weight on the scale.

That’s for me. A different propellant, different meter, different scale, might all mean a different way of thinking, a different method to follow. So, to be most clear: I am not saying not to weigh each charge, and I am not saying not to trust a meter. Let your chronograph and on-target results give you the best answer for your needs. This debate is probably as close to a religion as exists in reloading (well, along with full-length case sizing and neck-only case sizing). And most of the answer is plainly anticipated: if you’re throwing large-granule stick propellant (especially large amounts per charge), you might better ought to weigh them out, but if you’re throwing a small-grained stick propellant, a good meter might actually prove more accurate, given any questions about scale accuracy. Spherical propellant? Weighing that is truly a waste of time.

The point to this, beyond bringing up a topic for input-discussion, is to find some way to settle such questions for yourself. For me, and likely for you, the ultimate answer is founded in the confidence we can have in whichever is the primary dispensing apparatus: the scale or the meter.

[Ballistician and Olympic Shooter, Ken Johnson, shares his thoughts on this topic in his piece on Precision propellant.]

Check out Midsouth offerings HERE and HERE

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

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.