Category Archives: Ammunition

ammo, or ammunition category will be host to all topics related to factory ammo and ammunition. Everything from 22 LR to Bulk Pistol Ammo will be discussed here.

RELOADERS CORNER: Priming 3

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Correct primer ignition is a key to consistent velocities and good accuracy, and maybe even survival! Let’s make sure the primer pops proper. Read how…

Glen Zediker

Last two times we’ve looked at the tools and process of seating primers and also the thing itself. This time let’s take it another step and prefect the important step of priming a centerfire case.

primer pocket uniforming
Very important step, in my mind, in the reloading process: uniforming primer pockets.

 

As gone on about in the first article, it’s very important to seat each and every primer flush to the bottom of the cartridge case priming pocket. Tool choice has a whopping lot to do with how well attaining that goal can be reached, and that’s because it is a “feel” operation.

However! Probably the biggest asset to correct primer seating is a primer pocket that’s correctly dimensioned and correctly finished. And this, in effect, removes some of the importance or contribution of the “feel” needed and that’s because when the primer stops it will stop flat and flush. If the pocket is what it should be.

With the exception of a very few (and expensive) cases, the primer flash hole and the primer pocket itself are punched, not drilled and milled. That’s done, of course, in the interest of efficiency in producing the case. That manufacturing process, though, hain’t perfect.

Cross-section a case head and you’ll see that the inside bottom of the pocket is a little bowl-shaped; the corners aren’t square, which means the bottom of the pocket isn’t flat all across. Since the bottom of a primer cup is indeed flat, it’s way on better if these surfaces are a match.

primer pocket uniforming

A “primer pocket uniformer” fixes this to the same level it would be had it been machined: it will be at “blueprint” specs. A uniforming tool also sets pocket depth and will correct a shallow pocket. And again, the flat primer cup mated with an equally flat primer pocket bottom results in a truly well-seated primer.

In my estimation, I think this is an even more important procedure or preparation step for those using any automated or semi-automated priming process, such as encountered on a progressive-style press than it is for “precision” handloaders. In short: the less feel in the tool that’s available to guide you to know the primer has seated completely is offset a whopping lot by the assurance that flat-to-flat flush contact results pretty much just from running the press handle fully.

primer pocket uniforming tool
Primer pocket uniforming is done fastest and easiest with a tool that chucks into a drill. There are many available, and I recommend getting a “fixed” depth design. One thing: unlike virtually all other case-preparation steps, pocket uniforming is usually best one on once-fired, not new, brass. That’s because the pockets can be a little difficult for the tool to enter when the pockets are at their smallest, which they will be as new.

It’s another step, though, that adds time and tedium to the reloading process. Add power and it’s a lot easier, and, for the majority, has only to be done once. True, after enough firings a pocket will get shallower, and it will also be getting larger in diameter. Usually the increased diameter outruns the loss of depth in signaling the end of case life.

I use mine in place of a primer pocket cleaning tool. There is zero harm in running a uniformer each use for reloading. Uniformers are available as fixed- and adjustable-depth. I generally recommend getting a fixed tool, and then trusting it. Setting depth on an adjustable model is tedious, and critical. Too deep can weaken the case.

uniformed pocket
Here’s a little (important) something that you might notice after uniforming primer pockets. The case on the right shows very clear primer anvil impressions, and that’s because this primer was seated fully flush into a uniformed pocket; the case on the left was not uniformed and likewise the primer was not fully seated flush (couldn’t be).

If you’re wanting to load once-fired mil-spec cases, or have to load once-fired mil-spec cases, then the original primer crimp must be removed. A primer crimp is small lip of brass that’s pinched into the primer edge during the primer seating process. It holds the primer in place against inertia-induced movement that might unseat it. Now, you never ever need to worry about crimping your own ammunition. All that matters to us is removing the excess brass residual from the original crimp. The most simple, and fastest, way is using a primer pocket swaging tool. These are either press-mounted or stand-alone stations. Just run it, run it out, and the pocket has been swaged to unimpeded roundness again. It is possible to use a uniformer to remove crimp, but it’s a tool for another job and, almost always, it’s best to use specific tools for specific jobs. It’s a difficult chore with a uniformer, and the uniformer also may not smooth the entryway adequately.

primer pocket swaging tools
If you need to remove the crimp from mil-spec cases, get a swager. It’s the best tool for the job. They’re easy to use, and, as with other such processes, has only to be done once for the life of that case. After swaging, by all means run a uniformer if wanted. Check out tools HERE

Overall, get a swager and keep it simple. They’re not expensive, they’re easy to use, and, as with other such processes, has only to be done once for the life of that case. After swaging, by all means run a uniformer if wanted.

Should primer pockets be cleaned? Why not… There is probably no influence on accuracy if the pocket is dirty or spotless, but, why not… Deprime prior to case cleaning to get that area treated. I preach heavily on the virtues of a stand-along decapping station to keep grit out of the sizing die. A primer pocket cleaner is fast and easy to use, but, as mentioned, I instead just run a uniforming tool in its place.

As said a few times in this series, the most important thing is to know that the primers (all of them) have seated to at least slightly below flush with the case base. Just seeing that does, in no way, mean each primer is seated to perfection. There are variances in (un-uniformed) primer pocket depths. At the least, one more time, uniformed pockets will or sure should take a big step toward providing more certainty.

A “high” primer, one that’s not seated fully to the bottom of its pocket, results in a “soft” strike from the firing pin, and that’s because some of the inertia/energy in the speeding pin is siphoned away because it first will fully seat the primer… However! There’s another, even more important reason all primers should be seated fully: When used with a rifle having a floating-style firing pin, which is an AR15, the normal and unavoidable inertia-induced firing pin movement upon bolt closing will result in the firing pin tip contacting the primer. It will bounce or tap off the primer. If the primer is sitting out farther, there’s a greater likelihood of setting off the cap. That’s called a “slam-fire” and its aftermath ranges from shaken nerves to shrapnel infestations about the facial area.

AR15 firing pin indentation
Yikes! Here’s a round chambered and then pulled from one of my AR15s. Floating firing pins can “tap” off a primer, it’s intertia-induced. A more sensitive primer, and it could have gone off. This is not “supposed” to happen via rifle design, but, well, here it is. Make double-dang sure all the primers are seated below flush with the case head! It’s a problem with any floating-pin equipped rifle: M1A, M1, AR10, AR15. Primer composition matters. In this case, its resistance to detonation, and it should influence decisions on primer brands.

See what’s available 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: Priming, Part 2

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Last time the tooling and process of seating a primer got detailed, and now more details about The Thing Itself. Read all about it…

primer close up

Glen Zediker

A primer consists of a brass (usually) cup filled with impact-detonated explosive compound, lead styphate specifically. Right. Primers explode. The compound starts as liquid, not that that matters, and while it’s still wet, a triangular metal piece called an “anvil” is positioned in the opening. When it’s hit by the firing pin, the center of the cup collapses, squeezing the explosive compound between the interior of the cup and the anvil. That ignites the compound and shoots a flame through the flash hole. That ignites the propellant.

There are two primer sizes, and then type variations. The two sizes are “small” and “large.” For example, .223 Rem. uses small, .308 Win. uses large. Rifle primers and pistol primers are not the same, even though they have diameters in common. Rifle primers have a tougher cup, and, usually, provide a hotter flash. Do not substitute pistol primers for rifle primers! Some pistol shooters using very high-pressure loads substitute rifle primers, but also often need to increase striker impact power.

Variations: There are small variations in primer dimensions, heights and diameters, and also variations exist in new-case primer pocket dimensions, among various brands, and, of course, lot-to-lot variations can and do exist within any one brand. Usually, these variations are not influential to suitability. Usually. However! On occasion, small diameter variations can affect how well different primers will feed through various make priming apparatus. This can and has become a hitch in some progressive loading machines. Cup height variations can lead to seating depth (primer height) issues.

Remington 7-1/2 primers
I have my “go-to” primer, as do most, but I’ve found best results in certain circumstances with another brand. I will not vary primers, though, in my tournament ammo for any one day: as with propellants and bullets, each leaves a different residue in the bore, and that will, not can, influence zero making the switch. In other words, I won’t use CCI for short-line loads, and Remington for 600-yard ammo, not on the same day.

There are also “magnum” primers. These have a hotter spark. They are engineered to deliver a stouter kick-off to larger, more dense columns of slower-burning propellant. They also work well with spherical-type propellants (less air space between the granules). There are also “match” primers. These ostensibly are more consistent quality. Not all manufacturers offer these options. If they do, unless you have a scheme or more carefully-considered reason, just go with what fits your application. There’s no need for match primers in blasting ammo. There are, no doubt (and no doubt significant) differences among varying brand primers with respect to “output.” As mentioned earlier on, there are also pretty well-known tendencies that are either more or less preferable among varying primer brands.

The primer is, in my experience, the greatest variable that can change the performance of a load combination, which is mostly to say “pressure.” Never (never ever) switch primer brands without backing off the propellant charge and proving to yourself how far to take it back up, or to even back it off more. Don’t deny this one.

I back off one full grain of propellant to try a different primer brand.

Finding the best-performing primer for any particular combination of cartridge, bullet, and propellant isn’t just always as easy as putting a “match” primer in there. I have my preference, and it’s what I try first, but, to be certain, sometimes best accuracy and consistency (related) come with another. Again, it’s a combination of propellant fill volume, burning rate, propellant type (single-base, double-base, extruded, or spherical), and column “packing” density that favors either a “hotter” or “cooler” flash.

Priming cup composition also factors mightily in my final choice, and that’s a big factor in some semi-autos. More next time.

primer tray
Here’s handy. A primer “flip” tray puts all the primers in the sams orientation and orients them for easy loading into a primer magazine feed tube for use in many automated systems. See what’s available at Midsouth HERE

SAFETY
Do be extra careful handling primers! No kidding. It’s the most explosive element in a cartridge, and it’s intended to be detonated from impact, so… Wearing safety glasses at the loading bench might seem nerdy, but it’s wise. Likewise, and this has happened way on more than once, but, fortunately, never yet to me, is a mass detonation of primers contained in a feeding device, such as a primer feeding magazine tube. Such circumstance is grave indeed. Progressive loading machines, as well as many bench-mounted appliances, use a tube magazine that contains the primers. This tube must be filled, like any magazine. Make sure you know when full is full, and don’t try to poke in one more. This is usually when “it” happens. Remember, primers are detonated via pressure. Said before, but important enough to say again now: Never (ever) attempt to more deeply seat a primer on a loaded round. And keep the priming cup (the tool part that holds the primer for seating) clear of all debris. I’ve heard tell of brass shavings, leftover tumbling media, and the like, getting between the primer and the tool cup, and forming its own little firing pin.

See what’s available 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.

New Hornady Products for 2018

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Hornady has just announced their new products for 2018, from the much anticipated new reloading tools, to innovations in ammo and projectiles, Midsouth is eager to fill our shelves with their new offerings! Read on for a brief breakdown of what’s coming soon!

New in Reloading:

Cordless Vibratory Powder Trickler:

Some cool tools are on their way from Hornady MFG., like this Vibratory Trickler, which makes “quick work of various reloading chores!”

The Vibratory Trickler, powered by two AAA batteries, features variable settings to trickle all kinds of powders, ensuring the precise amount for each charge. Its modular design means you can use it with or without the base and also makes cleanup quick and easy.

Featuring:

  • Trickles all powders
  • Light-up LED screen
  • High, low, and variable trickle settings
  • Use in base or outside of base
  • Weighted for stability
  • No-slip base

Hornady Rotary Case Tumbler:

hornady rotary case tumbler

Clean and polish brass cartridge cases to a brilliant shine with the rotary action of this tumbler, coupled with its steel pin tumbling media (included). Use in conjunction with Hornady® One Shot® Sonic Clean Solution.

Six-liter drum holds 5 pounds of brass cases. Set tumbler to run for up to eight hours in half-hour increments using the digital timer.

Check out all the new items coming to our reloading category by clicking here!

New Projectiles:

Speaking of reloading, lets take a look at some of the new projectiles being developed by Hornady!

hornady dgx bonded bullets

DGX Bonded®

The DGX® Bonded (Dangerous Game™ eXpanding) bullet features a copper-clad steel jacket bonded to a lead core to provide limited, controlled expansion with deep penetration and high weight retention. Bonding the jacket to the core prevents separation from high-energy impact on tough material like bone, ensuring the bullet stays together for deep expansion.

DGX® Bonded bullets are built to the same profile as the corresponding DGS® (Dangerous Game™ Solid) bullets but expand to 1½ to 2 times their bullet diameter.

Thicker Jacket

The thicker 0.098” copper-clad steel jacket of DGX Bonded sets it apart from other dangerous game bullets, allowing it to tear through tough material like hide, muscle and bone.

Controlled Expansion

DGX Bonded features a flat nose with serrated sections to deliver a uniform expansion from 100 to 150 yards and straight penetration, reducing possible deflections.

Bonded Jacket and Core

The bonding process locks the jacket and lead core together, improving the retained weight of the expanded bullet.

ELD-X and ELD Match Bullets:

eld-x hornady bullets

There’s also a few new calibers coming to the ELD-X line of projectiles. The Extremely Low Drag – eXpanding bullets are a technologically advanced, match accurate, ALL-RANGE hunting bullet featuring highest-in-class ballistic coefficients and consistent, controlled expansion at ALL practical hunting distances. You can find them right here at Midsouth!

New Ammunition:

There’s some interesting complete cartridges coming out this next year, and a few to really examine will be the subsonic line, the 6.5 PRC, and the new line of .223 ammo called Frontier®

New 6.5 PRC

The Ultimate Trophy Magnet

The name says it all! The 6.5 Precision Rifle Cartridge was designed to achieve the highest levels of accuracy, flat trajectory and extended range performance in a sensibly designed compact package.

The name says it all! The 6.5 Precision Rifle Cartridge was designed to achieve the highest levels of accuracy, flat trajectory and extended range performance in a sensibly designed compact package.

Utilizing moderate powder charges that result in repeatable accuracy, low recoil and reasonable barrel life, the 6.5 PRC produces high velocities for target shooting with performance well beyond 1000 yards.

Rifle makers currently chambering the 6.5 PRC include GA Precision, Gunwerks, PROOF Research, Stuteville Precision and Seekins Precision. Check back often as additional gun manufacturers confirm chambering the 6.5 PRC.

There’s a lot more to cover, and information is still coming in daily on the new products announced for next year. Stay tuned for a more in depth look at these items as we get a chance to demo them.

RELOADERS CORNER: 4 Steps To Improve Standard Die Performance

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It’s easily possible to improve the alignment and concentricity of a die set, and the result is getting closer to perfection in your ammo. Here’s how…

Glen Zediker

Last time I wrote about some problems some dies can have. A couple of those things mentioned had a thing or two to do with preparation and setup, and I said then that “next time” I’d address a few ways to improve the results from the dies you already have. So here it is, sizing die first:

Many of the parts that make up a die, including the die body itself, have threaded couplings to allow for adjustment. Well, threads have gaps and that means there’s some amount of free movement afoot, or “afloat” more correctly. If there were no gaps between threaded surfaces then there would be no threading possible. To see it, loosen a locking or jam nut from a die part, the seating die or decapping stem for instance, and wiggle the part. It wiggles… Taking steps to, at the same time, take out that play and improve parts alignment pays off.

ONE: Let the shellholder float. One of the easiest mods to make to improve all die ops is to remove the apparatus that secures the shellholder into the press ram. It’s usually a wire spring clip. Pliers get it gone. Now the shellholder is free to slip in and out, mostly out, of its slot in the press ram, and an appropriately-sized O-ring banded around the slot area keeps it secure. Head to a real hardware store and find one easy enough. This mod has done two things: one is that the spring clip usually cocks the shellholder so it’s not sitting flat and flush with the ram top, which means neither is the case it’s holding, so now it is; and, two, there is now a self-centering action since the shellholder is free to move a tad. Always keep in mind that we’re dealing with small “tads” (0.001s of inches) and even though it might not be visibly noticeable, this floating setup will result in better alignment.

shellholder clip
Here’s an easy trick that will, not may, improve alignment in die ops. The ultimate result from all these steps is a more concentric round of ammunition, and most seem to think that’s worthwhile… It is.

TWO: Flatten the die lock ring. The next little help is to get the die body and press ram as closely aligned as we can. There’s a lot of gap resultant from the helix of 14-pitch threads. After adjusting the die body downward to produce the amount of case shoulder set-back you want, run a case fully into the die and, holding pressure (lightly, not forcibly) down against the press handle, secure the locking ring. This will ensure that the die is sitting “flat” atop the press. Then ONLY install and remove the die using the locking ring itself! Never the die body. By the way, and this actually is important: I don’t like lock rings that secure via a set screw; I prefer those that offer a clamping-style effect. The little set screw will lever against the angled threads on the die body and that, alone, can tilt the lock ring.

handling die by lockring
Once you get the dies secured as outlined here, handle them ONLY by their lock rings. That ensures all the careful prep stays intact. It also means no change of altering the die height, an asset toward maintaining correct case shoulder set back and also consistent bullet seating depths.

If you’re using a standard-form full-length sizing die, it will have an expander ball or sizing button (either term applies the same, just varies with who’s literature you’re reading). This part is mounted to the decapping stem and functions to open up the inside case neck after the case neck has been outside-sized by the die interior area. Depending on the difference in diameters between the newly-sized case neck inside diameter and the sizing button diameter, that’s more or less stress and friction the neck endures.

clamp-style lock rings
I use clamping-style die body lock rings, like these from Forster. Those with a set screw can tilt the lock ring when the screw tightens in against the angled threads.

I’ve talked more than a few times about the value of polishing the expander to reduce friction, but you still need then to make sure it’s sitting dead center within the die. So…

THREE: Align the expander ball. There’s a little bit of “feel” involved in this step, but it’s not hard to develop. The idea is to tighten the locking screw that secures the decapping stem against movement while the expander ball is captive in the sized case neck. After adjusting stem height (and, by the way, noticing the relatively huge amount of free movement the stem has) run a case up fully into the die and then retract it until you feel the expander engage within the case neck. Stop there. Now apply a little pressure against the press handle going the other direction (as if running the case back up) as you tighten the lock ring on the expander stem. That just set the expander in the center. If you have the tooling to determine this, select a case that represents your better examples of case neck wall thickness consistency for ultimate results.

 

expander ball adjustment
When it’s possible, and it usually is, secure locks for the pieces-parts when they’re doing their jobs. For instance, tightening the lock on a decapping stem when the expander is holding inside the case neck helps bring the stem into centered alignment, and the expander along with it.

Moving to the “other” die, the seater, the first step is the same as for the sizing die: flatten its seat atop the press, and that’s done pretty much in the same as for the sizing die. Instead of running a case into the die, though, I set an adequate number of flat washers atop the shellholder to bear some pressure against the die bottom. Then…

FOUR: Center the seater stem. Just like with the decapping stem, there’s thread play in the seating stem. Move the stem more toward an aligned center by simply securing its lock nut when there’s a bullet bearing up against the seating plug. As said, select a case with consistent neck walls to get best results. Now. The only foible with this is when you change seating depths by threading the stem up or down. It’s easy enough to repeat this op-step, but remember to do it. The BEST defense against alignment issues is purchase and use of a “competition”- or “benchrest”-style seating die. I’m talking about those having a spring-loaded sleeve that accepts the case fully before being run up to engage the seating plug. But, those still need to have their seating plug centered following the same sort of process used in these other “tricks”: snug the lock over a little pressure. That only has to be done once, though, for this die type.

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.

REVIEW: A Long-Range Story: Hornady 4DOF Ballistics Calculator

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Here’s a new ballistics calculator that takes four important ballistic factors into account, not just BC, to provide radically more precise calculated bullet flight figures. Here’s how it works…

4DOF

by Richard Mann

The new Hornady 4DOF ballistics calculator is so precise because it combines what Hornady calls the Four Degrees of Freedom. In other words, it takes into account windage, elevation, range, and angle of attack to generate a drag coefficient.

4 DOF

Recently, a few magazine editors visited for a week. Egos were on display and opinions were as thick as brass on the range at Gunsite Academy. The purpose of this get-together was to test about two dozen rifles, some purpose-built for connecting at extended distances. I have access to a 1,700-yard range and we spent the day there. My 17-year-old son, Bat, served as the official “range rat.”

After our 500-yard testing was complete, I told my associates I needed to get the DOPE (data of previous engagement) on my son’s African rifle. This would save a trip back to the range and give him some time behind the gun as payment for the support role he’d been filling.

The previous evening we had chronographed the Hornady Precision Hunter ELD-X load for the 6.5 Creedmoor my son would be using. That velocity, along with the bullet and related specifics were entered into Hornady’s 4DOF ballistic calculator, which is available online. I’d printed the results and our goal was to confirm elevation come-ups out to 500 yards. Amazingly, this was done with 5 shots; my son connected center target at 100, 200, 300, 400, and 500 yards. The data generated by the Hornady 4DOF calculator was spot-on.

Bat was having fun and shooting well, and since he now had the attention of the visiting editors, I figured, what the heck, he might as well try 700 yards. His first shot at 700 was about 2 inches high so he made a .25-MOA correction and fired again. Center hit! Now he really had their attention.

The next farthest target was at what I was told was 1,100 yards, and Bat asked if he could take a poke. I was skeptical and worried he’d blow the impression he’d already made on these experts, but figured the boy deserved a chance. The Hornady 4DOF ballistics calculator data called for a 38.25-MOA adjustment at 1,100 yards. I got on the spotting scope and told him, “Send it.” He did, and he missed high, by what appeared to be several feet.

I Instructed Bat to walk the reticle in the Bushnell 2.5-10X Engage riflescope — yes, this was a 10X riflescope — down 1 MOA at a time. At 3 MOA below center, I called the shot just left. (Wind is a terrible thing at 1,100 yards.) My instructions were to keep the same elevation hold but to also hold 2 MOA off the right edge. He pulled the trigger six times and achieved six hits. The onlookers were stunned, I however, was confused.

With the 4 DOF calculator from Hornady you can input your data and go to the range with total confidence it will be precise. Of course, remember, garbage in, garbage out. You have to input the right information.

4DOF printout

How could the Hornady 4DOF ballistics calculator data be so correct out to 700 yards and be off so much at 1,100? A range finder and a return to the Hornady 4DOF ballistics calculator answered the question. Instead of 1,100 yards, the target was at 1,048 yards. Resetting the Hornady 4DOF calculator to display come-ups in increments of 10 yards, it showed the proper correction for that distance to be 35.25 MOA. With our original 38.25-MOA correction we were 3 MOA or about 33 inches high. Had we known the correct range to the target, the 4DOF-generated data would have allowed for an easy first or, since we had a bit of wind, second-round hit.

What makes all this possible is the math and mechanics behind the Hornady 4DOF ballistics calculator system. Its four degrees of freedom, taking into account windage, elevation, range, and angle of attack, allow trajectory solutions to be calculated with a drag coefficient instead of a ballistic coefficient (BC). It’s also the first publicly available ballistics calculator capable of determining the accurate vertical shift a bullet experiences as it encounters a crosswind, which is known as aerodynamic jump.

By using Doppler radar and actually shooting bullets, Hornady calculates the exact drag curve for every projectile in the 4DOF Bullet Library. (Currently there are more than 100 projectiles from Hornady, Lapua, Berger and Sierra.) BC can change as velocity changes, a drag curve doesn’t. Explained simply, instead of using BC, which gives you a snapshot of a bullet at various distances; Hornady has created a video of the bullet’s flight. This allows the 4DOF calculator to predict drop with perfection at any distance, every time.

The takeaway from all this — the one that’ll matter to you and your ammo — is that the Hornady 4DOF ballistic calculator is extraordinarily precise. Taking data this exact to the field on a first try is as rare as 17-year-old boys who can hit at 1,100 yards, six times in a row.

Check it out HERE

Download the app HERE for iOS

Download the app HERE for Android

RELOADERS CORNER: Problems Dies Can Have

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Reloading problem? First make sure it’s not your tools… Here are a few things that can happen, and how to correct them.

Glen Zediker

Over years and years (and years) I’ve encountered a few factory-faulty sizing and seating dies, and associated pieces-parts. It’s not at all common, but it happens, or has happened, enough that I wanted to share a few stories as to what these problems come from, and how to identify (and correct) them.

As has been my norm here of late, yep: got a phone call from a fellow having problems with a new 28 Nosler. Took a while to get through this one… Turned out that the sizing die was the culprit. Wasn’t easy to sleuth but there’s a Zen tenet that paraphrases to this: If you’re not sure what something is, then carefully consider all the things that it is not; what’s left is the answer…

forster concentricity fixture
A concentricity fixture is a handy tool to help identify any issues a sizing or seating die has.

By the way, I’m not going to mention brand names for one good reason: I’ve seen or been presented with issues in dies from every major maker.

Sizing die problems I have either encountered first-hand or been witness to via my circle have most often been a full-length die that will not adequately set a case shoulder back where we want to take it. Conversely, it’s much more common to have a die that’s erring on the more extreme end of that, and erring toward “too much” sizing potential is logically a direction a die maker might take to accommodate more circumstances. Once the shellholder is making full and flush contact with the die bottom, that’s all she wrote. Continuing to turn the die body downward does nothing but stress the press and possibly damage the die. To get the case farther up into the die, either thin the shellholder top surface or grind the bottom of the die hisself. Neither are hand-tool operations! Get to a local gunsmith or machinist.

Look at a hair from your head and that’s ballpark 0.004-0.006 inches. It doesn’t take much at all to make the difference between smooth function and a bolt that won’t close.

loaded round runout
Check loaded rounds to point out bullet seater problems. Check sized rounds to point out sizing die issues. Removing the expander and checking neck runout on a sized round usually points out any problem with the die itself. It should spin with no to very little runout.

Check out Midsouth tools HERE

Most sizing dies are reamed one-piece, one-shot like a rifle chamber; however, that’s not always the method. Some are done in two or more steps, using two or more cutting tools. Clearly, consistency and correctness favors the one-piece reamer. Assuming that the reamer is correct and correctly used. I have encountered one die that just wasn’t concentric, body chamber to neck area. I figured that one out by sizing without the expander and checking runout, and also by finding that I could shift off-center axis by rotating the (marked) case and running through again. Normally, sizing a case without the expander in place results in a case that runs flat-line on a concentricity fixture. Reason is primarily because any inconsistency in the case neck walls get “pushed” to the inside case neck. But if there’s wobble in a case that’s been sized sans expander, then, son, you got a die problem.

A bent or bowed expander stem will, not can, result in an expander that’s going to cock the case neck one direction. I watch for that when I polish the expander button. As described here before, that process involves chucking the stem (lightly) in an electric drill and spinning the ball against some wet emery to give the ball a shine. If it’s wobbling during this operation, that’s a problem.

polished expander
With one particular brand of bullets (which were a tad amount smaller diameter than usual) I experienced inadequate bullet grip, insufficient to retain the bullet in the case neck on magazine-fed rounds. That wasn’t really a die problem, but the (simple) solution was to reduce the expander ball diameter. The die maker replaced the stem assembly for me so I didn’t have to apply that extra tension to rounds loaded with my usual bullet brand. When you polish the expander (and you will do that right?) notice if there’s wobble. Don’t accept it.

Seating die issues, in my experience, usually revolve around plain old straightness of the seating stem, and, once, the concentricity of the reamed case body area. If you have a seating die that increases runout compared to what a concentricity fixture showed on the sized case neck, it needs looked into. Additionally, always (always) check to make sure the seating plug (the area that fits over the bullet to push it into the case neck) is deep enough the the bullet tip does not make contact with the inside of the plug. That’s a sure way to get a bullet tipped off kilter.

bullet seating stem check
Always check to see that the tip of the (longest) bullet you use doesn’t contact the inside of the seating die plug. If it does it will get skewed.

Now. Most importantly: What to do if you suspect a tooling problem? Short answer is: SEND IT BACK. Don’t accept it. I know of no maker who won’t profusely apologize and promptly return a new one. The fixes I mentioned are for those who prefer to solve such issues, and also for those who have the means to effect repairs. The point to this article mostly is to be aware that problems can and do exist, and don’t accept them, whichever direction you seek for the solution.

No matter how precisely a die maker produced the parts, there is and will be some gap in threaded pieces. This can disguise itself as a “die” problem, but it’s really not. It’s a set-up problem. I did an article a good while back here on a few ideas on improving tool/case alignment via some set-up tricks, and maybe that should be the next topic under the Reloaders Corner banner.

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 Jump, Three

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In this final installment you’ll learn how to take bullet jump completely out of the equation, but it’s not just that simple… Here’s how to get the results you’re after. Keep reading…

Glen Zediker

There’s one more concept to consider to fully finish the topic of bullet seating depth, and it’s literally on the other end of the equation from discussions on bullet jump.

Last two articles were all about a combination of the evils of jumping bullets and also some ideas on reducing the ill effects, and hopefully to the point of zero measurable group size differences. I also mentioned that there are some bullets that just don’t tolerate jumping.

JLK 105 VLD
Bullets like this tend (a true Davis-drawn VLD) not to shoot well unless they start right on or very near the lands. I sho don’t know for certain, but I really think it has at least some to do with, for want of a better way to describe it, their leverage: it’s a lot of front end ahead of the first point of land diameter. These really long bullets don’t have to tip much to shift alignment relatively more.

For many (many many) years it’s been generally held that starting a bullet touching the lands is the easy ticket to better accuracy. That’s hard to disprove. It’s a tactic very commonly used by Benchrest and Long Range Rifle competitors, and savvy long-shot hunters. Now we’re talking about zero jump. Myself and many others have referred to this bullet seating tactic as “dead-length” seating. To be clear: it’s the cartridge overall length that has the bullet nosecone actually sitting flush against the lands (touching on whichever point along the nose that coincides with land diameter). Some literally take that a step farther and increase contact force such that the bullet is sticking into the lands one or more (sometimes several more) thousandths, actually being engraved by the lands prior to launch.

There are two ways to attain or approach dead-length. One is through careful measurement using something like a Hornady LNL Overall Length Gage. That tool should be paired with a bullet-length comparator, and Hornady has one of those too, as do others.

Measure enough bullets using a bullet-length comparator and you will find length differences in a box of most any brand. A comparator, as has been shown before in my articles (because it’s a very valuable tool to increase handloading precision), provides a more accurate means to measure bullet length. It’s a simple tool: the bullet nosecone fits into the opening on the gage, stopping at a point (determined by tool dimension) along the nosecone. Not all such gages coincide with land diameters because both comparators and land diameters vary from maker to maker. They are all “close” but perfect coincidence doesn’t really matter because a comparator will allow a reading at the same point of diameter regardless. Measuring from the base of a bullet to the bullet tip is inaccurate, and not nearly “good enough” to provide a precise enough measurement to venture into lands-on seating depth experiments. The reason measuring from base to tip isn’t good enough is because, especially in hollowpoint match-style bullets, there are relatively huge variations in the consistencies of the tips. I’ve measured easy 0.020 differences in a box of 100. Can’t make bank on that.

Using the combination of the gage that shows overall cartridge length that has the bullet touching the lands and the comparator to precisely record this length, it can then be reproduced via seating die adjustment.

Hornady LNL gage setHere’s a tool set shown many times in my books and articles this pair or something similar is necessary to negotiate this step in handloading. Check it out HERE and HERE at Midsouth.

If using this method, maintain whatever usual neck sizing dimensions are for your routine loads. There’s no need or benefit from lessening the case neck “tension” (which is the amount, in thousandths of inches, of the difference between resized case neck outside diameter and the resulting diameter after a bullet is seated). If that’s, say, 0.003 then keep it at 0.003.

There’s another, maybe better, method to follow if (and only if) you have a bolt-gun that’s to be fed one round at a time. By that I mean the rounds are not feeding up from a magazine but are being manually inserted into the chamber. That method is to reduce the case neck tension or grip to a level that the bullet is free enough to move within the case neck such that it seats itself when the round is chambered and the bullet makes contact with the lands. That’s awfully light in-neck resistance. It can’t be so light that the bullet falls into the case neck, but light enough that it can be scooted more deeply with little pressure. For a number it’s 0.001, minus, and half of that is workable if the case necks have been outside turned (so they are dead consistent in wall thicknesses and therefore will reliably “take” that little tension, meaning respond consistently to the sizing operation). Need a bushing-style sizing die to get that sort of control over the neck sizing dimension.

This method is often called “soft seating.” It’s, as said, very popular with competitive precision shooters. The bullet, keep in mind, isn’t just touching the lands, it’s actually engaging the lands to whichever degree or distance that resulted from overcoming the resistance from the case neck. If you feel anything more than slight resistance in chambering a round, that’s too much resistance. Chances are that any soft-seated bullet will stick in the barrel so extracting a loaded round will likely result in a big mess (elevate the barrel a little to keep the propellant from dumping into the action). Pushing the lodged bullet back out and looking at it carefully gives a good idea of how much resistance it’s overcoming. If the engraved area is much over 1/16-inch, increase the neck sizing bushing diameter to likewise loosen up the case neck. The amount of engraving has a whopping lot to do with the bullet jacket material (you’ll see more with a J4 than with a Sierra).

If you follow this method, then finish the die-seated bullets “out” 0.005-0.010 inches.

Redding sizing die bushing
It’s necessary to be able to fine-tune neck sizing dimension to experiment with soft-seating. A bushing-style sizing die is best. The bushing might also change for different brands or lots of brass if there are thicker or thinner neck walls. Clearly, outside neck turning is a step toward consistency in this sizing operation.

The reason this method can give the overall best results is because it’s accounting for teeny differences in bullet ogives and it also is adjusting itself for throat erosion. As gone on about in the last couple of articles, a barrel throat is lengthening with each round that passes through. What was touching the lands, or jumping 0.015, even one hundred rounds ago is no longer valid, and it’s totally corrupt five or six hundred rounds later. It’s no longer a precise setting, meaning a precise seating depth, and it has to be checked and reset as the barrel ages.

Again, this is not a casual experiment. The level of control and precision necessary to make it work safely and as expected is a step or three beyond what most reloaders are tooled up to deliver.

Will lands-on seating work for a semi-auto? Yes. But only with adequate bullet grip to retain the bullet firmly in the case neck, and that means the same tension that would be used with any other cartridge architecture, and that means a minimum of 0.003 inches difference between sized and seated outside case neck diameters. I do it often with my across-the-course High Power Rifle race guns. Clearly the “soft-seating” tactic is in no way wisely feasible in a semi-auto.

WARNING!
MOVING A BULLET OUT SO IT TOUCHES THE LANDS WILL (not can) INCREASE LOAD PRESSURE! Even going from 0.001 off to flush on will spike pressure. When the bullet is in full contact it’s acting like a plug. I strongly suggest backing off one full grain (1.0 grain) before firing a bullet touching the lands. Then follow my “rule”: work up 0.2-grains at a time but come off 0.5-grains at a time! If there’s ever any (any) pressure symptom noted, don’t just back of a tenth or two, that’s not enough, not considering all the other little variations and variables that combine to influence the behavior of the next several rounds you’ll fire.

THREE REASONS DEAD-LENGTH SEATING WORKS
ONE: Accounts for and overcomes any minor variations in bullet dimensions.
TWO: Minimizes bullet jacket disruption on entry.
THREE: Virtually eliminates misalignment between bullet and bore.

SIDE NOTE
If you’re one who, as many readers have suggested to me, has found that seating a bullet to touch the lands is the only way they get good groups, consider the above three reasons this seating method works and then interpret. If, and this is more common than we’d like to see, you’ve got a factory bolt-action rifle the chamber is likely to be overly generous in size or a tad amount non-concentric, or both. The case wall consistency and also sizing and seating tooling, or all three, might likewise be sub-par. In other words: lands-on seating is overcoming a few rifle issues, not, in itself, proving it’s the one-way ticket to great groups. Mostly, getting the bullet into the lands essentially straightens out alignment of the whole cartridge sitting in that (maybe) big chamber.

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 Jump 2

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Tips that help take bullet jump out of the accuracy equation. Find out how!

leade
This is an aluminum staub cut with a chamber reamer. It’s easy to see the transition to the lands. The more smoothly a bullet enters the lands, the better it will shoot. When seating depth can’t be idealized, choosing a “gentle” bullet is the best defense against ill effects of jump.

Glen Zediker

Last time I shared some insight about bullet “jump,” and specifically with respect to the viability of setting up a “zero-jump” chamber/ammo combination.

To hit the highlights: Jump is the gap the bullet must traverse when it leaves the case neck to engage the lands or rifling. Generally, best (and better) accuracy comes with this gap is reduced to a minimum amount, or at the least reduced. Better is better.

To go farther into this topic, it’s worthwhile to move the bullet around, seating it more or less deeply (nearer or farther from the lands at rest) to maximize accuracy. Clearly, there’s a limit on cartridge overall length if the rounds have to fit into a magazine box so they can feed right. In NRA High Power Rifle competition, the AR15 pilots are specifically not allowed to have the rounds feed from the magazine in semi-auto mode; each round must be loaded into the chamber one at a time for the “slow-fire” segments, which includes the 600-yard event. That means competitive High Power shooters using AR-platform rifles are free to move the extra-long 80+ grain .224-caliber bullets out to near or on the lands when chambered. That doesn’t really matter but it explains the popular “Wylde” chamber we tend to use. It’s got a long enough throat to free more case volume and also provide a bigger “expansion chamber” for burning propellant gases, but it’s not as long as a NATO-spec so should perform better with bullets that do have to be loaded deeply in enough to fit the magazine box. Something like a Sierra 80gr or 82gr Berger won’t usually shoot worth a flip loaded to mag-length. That bullet, and others similar, are simply too dang long for a .223 Remington case. A huge amount of the bullet swallows up the case interior.

Sierra bullets compared.
It’s not all in the ogive specs, but it’s influenced by it, because those specs influence the overall profile of the bullet. Here’s a .224 Sierra 77gr MatchKing next to an 80gr MatchKing. The first is approximately 8 calibers, the 80 is approximately 12. The marks indicate the location of the first point of coincidence of land diameter. Considering the overall profile differences, it’s pretty clear that the 77 jumps with better results when each is loaded to the same cartridge overall length. There’s just 3grs difference in these bullets but they’re worlds apart in both tolerance and performance.

The best defense against ever worrying over jump, meaning whether you’re getting good accuracy regardless of the amount of bullet jump (well, at least within reason…) is bullet choice. Specifically, a tangent-profile bullet with a conservative ogive. Recollecting from some materials I did a while back, a “secant” profile is a sharper taper-in from bullet body to bullet tip; a tangent is a smoother transition. Secants, more or less, have a “shoulder” indicating a more abrupt taper rather than a smooth arc. For examples: true VLD (very low drag) and the Hornady A-Max are secant.

Bullets with relatively shorter nosecones and relatively longer bearing areas (length of the bullet that’s in contact with the rifling) are likewise more tolerant of jump.

Sierra 69, JLK 70 VLD
Here’s an example of different .224 bullet profiles at essentially the same weight. A Sierra 69gr MatchKing on left and a JLK 70gr VLD. The tangent 8-caliber-ogive (approximate) Sierra shoots great when it’s jumping; the secant 15-caliber-ogive VLD tends not to shoot well at all unless it starts touching the lands.

There’s been a trend for many years now toward creating bullets with higher ballistic coefficients. Worthwhile pursuit! Only issue is that when a bullet design features better aerodynamics, the features of that are, yep, longer nosecones with shallower angles. The ogive (what I’ve been more descriptively calling the nosecone because it’s easier to picture) usually is expressed in calibers. Technically it’s “calibers of ogive,” and that’s the ogive radius divided by the caliber. To me it’s easier to picture looking at the “other side” of the equation: the arc that scribes the profile in multiples of the bullet’s caliber. So, a 7- to 8-caliber ogive is a tighter circle (more rounded profile) than a 12- or 15-caliber ogive. Most of the “high-BC” profiles use a 15, some more. In other words, they’re stilettos.

calibers-of-ogive
Here’s an illustration of calibers-of-ogive from Sierra. That transition area from bullet diameter to first point of contact with the lands (which will be land diameter, and at least 0.005 smaller) has influence on how well a bullet endures jump. A lower-number is favorable in this regard. In this illustration the ogive radius, 2.240 inches, divided by the caliber, 0.308, gives 7.27. That should tolerate jump well.

I’m kind of breaking this down farther and faster than exercising good technical care in covering this topic should warrant, but: comparing both same-weight and same-caliber bullets, the longer it is the more sensitive it’s going to be to jump.

I have shot way too many high-X-count 300-yard cleans with bullets jumping 0.030+ inches to say that it’s not possible to have good accuracy unless jump is minimal. I admit that’s only a 1 moa group. I’m also using what some makers call a “length-tolerant” bullet, and specifically that’s a 77gr Sierra Matchking, and the same goes for a Nosler 77 or Hornady 75 HPBT (not A-Max). It’s the bullet form, not just its weight, that has the strongest influence on all this.

So, do you have to abandon better ballistics to attain better accuracy? Maybe. At least to a point. With the smaller calibers, which don’t have other advantages larger calibers have simply by virtue of weight and sectional density, there tends to be an effectively greater discrepancy between the lighter and heavier (again, it’s really shorter and longer) bullet ballistic performances.

A rifle with a generous-length magazine box provides greater jump-reduction via loaded round architecture. If there’s enough room, a bullet can be scooted out to the limit of the space within the box.

As always, well at least usually, there are tools! Get them and use them. A gage “set” from Hornady is well advised. There are others similar. I’ve been using their LNL Overall Length Gage and Bullet Comparator for many years and receive needed results. The first tool indicates the seating depth that touches the lands, and the second provides more reliable and accurate means to measure and record it.

Hornady LNL gage
This Hornady LNL gage pair gives you the tools needed to determine the jump you’re getting with the bullet you’re using. Check it out HERE

The leade, which, again, is the transition to the lands and determined by the chambering reamer (or throating reamer if custom-done) does influence tolerance for jump. The shallower the angle the better, but, that’s a two-edged issue. Take a commonly-used 3-degree leade and make it a more preferable 1.5-degree leade and that takes way on more than double the distance (length of cut) to attain. Again, when there’s a magazine getting in the way of bullet seating depth flexibility, a shallower leade eases transition into the barrel bore for a jumping bullet, but also increases jump. There are some cartridges, like David Tubb’s 6XC, that were designed specifically to “perfect” all these relationships: magazine-mandated cartridge overall length, bullet choice, and leade in, and it’s one reason it owns the records it does. Otherwise, it’s often a compromise… But don’t compromise accuracy for anything. A smaller group is, in the long run, the best defense against both wind and distance when it comes to hitting a target. Reliable feedback equals correct adjustments.

The preceding was adapted from Glen’s newest book, Top-Grade Ammo, available here at Midsouth. For more information on this book, and others, plus articles and information for download, visit ZedikerPublishing.com

RELOADERS CORNER: Bullet Jump: does it really matter? (Part One)

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The distance a bullet travels to enter the lands is a topic of much concern to the precision shooter. This series takes a look at why it matters, and also when it doesn’t…

Glen Zediker

bullet jump
Here’s jump: it’s the distance from the end of the case neck portion of the chamber to the first point the bullet will engage the lands or rifling.

Bullet jump: the open space a bullet must span until its first point of sufficient diameter engages the barrel lands.

Last week I had a long phone conversation with a fellow who had been bitten by two bugs, two somewhat conflicting bugs (at least seemingly so on the onset). The one was a regrouping equipment project for USPSA-style practical rifle competition, and the other was for a desire to maximize accuracy, which is to minimize group size. This fellow had been involved in competition long enough to decide to stay with it, and was re-upping his AR15 upper with a new custom barrel. He wanted to have the best accuracy he could buy, and that’s a worthwhile pursuit as long as there’s a budget that supports it.

The subject of bullet jump became the dominant topic.

Yep, he had read my books and a few others and developed the impression that minimizing bullet jump was one crucial component to maximizing accuracy. That’s fair enough. I’ve gone on about it, as have others. Adjusting bullet seating depth can make a big, big difference in shot impact proximities. However! The reason bullet jump matters — usually — is largely, almost exclusively, because of some bullet profiles being more finicky than others. Namely the longer and spikier “very-low-drag” type bullet profiles.

The first point of “major diameter” on a bullet is what coincides with the land diameter in the barrel. If that’s a .22 caliber with 0.219 diameter lands, then the first point along the nosecone of a bullet that’s 0.219 is the distance. Gages that measure this distance (Hornady LNL for instance) aren’t necessarily going to provide perfect coincidence with land diameter, but still provide an accurate bullet seating depth that touches the lands.

If you find the cartridge overall length, which really means bullet seating depth, that touches the lands (coincides with land diameter) then subtract that from what you then measure when the bullet is seated deeply enough to fit into a magazine box, that right there is the amount of jump.

Hornady LNL gage
There are other ways to find it, but the Hornady LNL Overall Length Gage makes it easy. I’d be lost without this tool. Use it to determine the current distance to engage the lands for any bullet you’ll use (it works also as a way to monitor throat erosion). Get one HERE

Dealing with an AR15, or any other magazine-fed rifle, assuming we are wanting the rounds to feed from the magazine, is that there’s a finite cartridge overall length that will fit into the magazine. So. We’re almost always going to be dealing with some amount of jump, unless one or two things can be manipulated to reduce or eliminate it.

AR15 loaded magazine
A box magazine sets the effective limit on overall cartridge length. Getting a bullet to sit close to the lands when the round is chambered requires either some trickery in chambering specs or, mostly, bullet selection. However, with selection there is also limitation. For safety’s sake, no factory loaded round is going to approach lands-on seating structure. When a bullet touches the lands at rest, pressures will, not can, spike. All good, if it’s accounted for. This sort of “fine-tuning” is strictly a (careful and knowledgeable) handloader’s realm.

The one is that the influence of rifle chamber specs with respect to either more or less jump is pretty much exclusively in the leade or throat. That’s the space that defines the transition from end of the chamber case neck area to entry into the lands. The closer the lands are to the chamber neck area the shorter the jump will be with any bullet. That is the leading difference between a SAAMI-spec .223 Remington chamber and a 5.56 NATO chamber. The NATO has a much longer throat. I’ve written on that one a few times…

A shorter throat has goods and bads. The main good is that, indeed, any and all bullets are going to be closer to the lands in a round loaded to magazine-length.

But the “two” in the things that influence jump is bullet selection. It is possible to find a combination that will easily have the bullet sitting right on or very near the lands at the get-go. That’s going to be a short, and light, tangent ogive bullet within a SAAMI-spec .223 Remington chamber, or (and this is what I have done) a barrel chamber finished using a throating reamer to get even closer. In general: the nearer the first point of major bullet diameter (remember, that’s the land diameter) is to the bullet tip, the shorter the jump will be, and that’s because this point is “higher.”

Hornady 52gr HPBT
Looking through a good factory loading manual down amongst the “lighter bullet” selections, take a notice of the overall round length used in the test ammo. Magazine box maximum for an AR15 is 2.25 inches (it’s actually 2.26 at a maximum, but don’t cut it too close). If you see a length less than that, then there’s a bullet that can be seated on or near the lands at magazine length. Simple.
Here’s a great example that I can tell you absolutely will engage the lands in an AR15 loaded to magazine length. As a matter of fact it will be over 0.020 into the lands at magazine length, so certainly must be loaded to an overall length well less than that… It also shoots little groups. Check it out HERE

Throat erosion is going to lengthen the throat. Can’t stop that. The cartridge structure that was jumping, say, 0.005 on a new barrel is jumping more than that after literally every round fired through it. After some hundreds of rounds it’s jumping a few multiples of 0.005. (How much or how many is not possible to forecast because way too many factors influence the amount and rate of throat erosion. Just have to keep checking with the gage I suggest you purchase.) This is the reason I specify a custom dimension to get reduced jump: with the right hands using a throating reamer it’s easily possible to maintain land contact at magazine length seating even after a lot of rounds have gone through. Bullets will begin being seated more deeply and then get nudged out as the throat erodes.

So, where the conversation ended was this: If (and only if) someone is willing to take the time and make the effort to carefully establish and then control a reduced or eliminated amount of magazine-loaded jump then, yes, it’s a fine idea! It’s also an idea that likely will result in the best accuracy. I’ve done it in one of my AR15 match rifles, and it’s the best shooting I’ve ever owned. The hitch is that the rifle becomes what I call a “one-trick pony.” It’s not always going to accept bullets and loaded round architectures that stray from the carefully calculated dimensions originally set down. It’s also not likely going to perform safely with every factory-loaded round out there, and you can forget (totally forget) ever firing a NATO-spec round.

There’s a whopping lot more to this whole topic, and we’ll look at the other end of the spectrum next time.

The reason that reduced amounts of bullet jump increase accuracy, in a perhaps overly simple but entirely correct way to understand it, is because there’s simply less potential for disruptive entry into and lands and then through the bore. There’s less misalignment opportunity, less jacket integrity disruption opportunity. There is a lot more that can be discussed in finer points, of course…

The preceding was adapted from Glen’s newest book, Top-Grade Ammo, available here at Midsouth. For more information on this book, and others, plus articles and information for download, visit ZedikerPublishing.com

RELOADERS CORNER: REALLY Understanding Case Neck Sizing

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Determining and setting the correct case neck diameter is a critical, crucial step in the handloading process: Here’s all you need to know!

sizing die bushing

Glen Zediker

Here’s another I get (too many) questions about, and when I say “too many” that’s not at all a complaint, just a concern… This next hopefully will eliminate any and all confusions about this important step, and decision, in the reloading process.

Basics: A cartridge case neck expands in firing to release the bullet. If the load delivers adequate pressure, it can expand to the full diameter allowed by that portion of the rifle chamber. That diameter depends on the reamer used. After expansion and contraction, the case neck will, no doubt, be a bigger diameter than what it was before being fired.

Back to it: To get a handle on this important dimension, the first step is tools. As always. A caliper that reads to 0.001 inches will suffice.

You need to find three outside diameter numbers: fired case neck diameter, sized case neck diameter, loaded case neck diameter. If you know the loaded case neck diameter then it’s likewise easy to find out the case wall thickness, or at least an average on it if the necks aren’t perfectly uniform (and they won’t likely be unless they’ve been full-on outside case neck turned).

Case neck sizing diagram
“All the math” works in either direction. Here’s how.

A fired case neck has to be sized back down to a dimension that will retain a bullet from unwanted movement (slippage) in the reloaded round. Case neck “tension” isn’t really an accurate term, in my mind, so I prefer to talk about “constriction.” The reason is that making a case neck diameter smaller and smaller does not, after a point, add any additional grip to the bullet. Once it’s gotten beyond maybe 0.005 inches, it’s just increasing the resistance to bullet seating not increasing the amount of tension or retention of the case neck against the bullet. The bullet is resizing the case neck, and probably getting its jacket damaged in the process. If more grip is needed, that’s where crimping comes in…and that’s (literally) another story.

IMPORTANT
Always, always, account for the “spring-back.” That is in the nature of the alloy used to make cases. If brass is sized to a smaller diameter it will spring back plus 0.001 inches bigger than the tool used; if it’s expanded to a bigger diameter, it will spring back (contract) to 0.001 inches smaller than the tool used. This is always true! The exception is that as brass hardens with age, it can spring back a little more.

How much constriction should there be? For a semi-auto, 0.003 is adequate; I recommend 0.004. For a bolt-action, I use and recommend 0.002, and 0.001 usually is adequate unless the rifle is a hard-kicker. See, the main (main) influence of more resistance in bullet seating is to, as mentioned, set up enough gripping tension to prevent unwanted bullet movement. Unwanted movement can come from two main sources: contact and inertia. Contact is if and when the bullet tip meets any resistance in feeding, and gets pushed back. Intertia comes from the operation and cycling of the firearm. If there’s enough force generated via recoil, the bullets in rounds remaining in a magazine can move from flowing forces. However! That also works literally in the other way: in a semi-auto the inertial force transmitted through a round being chambered can set the bullet out: the case stops but the bullet keeps moving. I’ve seen (measured) that happen with AR15s and (even more) AR-10/SR-25s especially when loading the first round in. Put in a loaded magazine, trip the bolt stop, and, wham, all that mass moves forward and slams to a stop. Retract the bolt and out comes a case with no bullet… Or, more usually, out comes a case with the bullet seated out farther (longer overall length). Never, ever, set a constriction level on the lighter side for either of these guns.

Most seem to hold a belief that the lower the case neck constriction the better the accuracy. Can’t prove that by me or mine. If there’s too much constriction, as mentioned, the bullet jacket can be damaged and possibly the bullet slightly resized (depending on its material constitution) and those could cause accuracy hiccups. If it’s a semi-auto and constriction is inadequate, the likewise aforementioned bullet movement forward, which is very unlikely to be consistent, can create accuracy issues, no doubt. My own load tests have shown me that velocities get more consistent at 0.003-0.004 as compared to 0.001-0.002.

Benchrest competitors use virtually zero constriction, but as with each and every thing “they” do, it works only because it’s only possible via the extremely precise machining work done both in rifle chambering and case preparation. It is not, decidedly not, something anyone else can or should attempt even in an off-the-shelf single-shot. As always: I focus here, and in my books, on “the rest of us” when it comes to reloading tool setup and tactics. Folks who have normal rifles and use them in normal ways. And folks who don’t want to have problems.

So, find out what you have right now by determining the three influential diameters talked about at the start of this article. Most factory standard full-length sizing die sets will produce between 0.002 and 0.003 constriction. Getting more is easy: chuck up the expander/decapper stem in an electric drill (I use oiled emery cloth wrapped around a stone), and carefully reduce the expander body diameter by the needed amount, or contact the manufacturer to see about getting an undersized part. I’ve done that.

polish expander
It’s easy to increase case neck constriction if you’re running a conventional sizing die setup that incorporates an expander or sizing button. Just make the button diameter smaller; then it won’t open up the outside-sized case neck as much as it is withdrawn from the die and over the expander.

If you want less constriction than you’re currently getting, about the only way to do that one is hit up a local machinist and get the neck area in the die opened by the desired amount (considering always the 0.001 spring-back). Or get a bushing-style die…

Redding S Die
It’s not perfectly necessary to use an inside case neck expanding tool if you’re using a bushing-style die. I think it’s wise for a multitude of reasons I’ve gone on about in the past, and may should again, but if the math is carefully done, and the cases are all same lot, outside neck reduction will result in consistent inside case neck diameter sizing. Example: Case neck wall thickness is 0.012, outside sized case neck diameter is 0.246 (from using, remember, a 0.245 bushing), then the inside case neck diameter will be 0.222, and that will be a 0.002 amount of bullet constriction (0.224 caliber bullet).

The bushing-style design has removable bushings available in specific diameters. Pick the one you want to suit the brass you use. If you run an inside case neck expanding appliance along with a bushing die, usually a sizing-die-mounted “expander ball” or sizing button, make sure you’re getting at least 0.002 expansion from that device. Example: the (outside) sized case neck diameter should be sufficiently reduced to provide an inside sized case neck diameter at least 0.002 smaller than the diameter of the inside sizing appliance. That’s done as a matter of consistency and correctness that will account for small differences in case neck wall thicknesses. And when you change brass lots and certainly brands, measure again and do the math again! Thicker or thinner case neck walls make a big difference in the size bushing needed.

Check out a few ideas at Midsouth HERE

The preceding was adapted from Glen’s newest book, Top-Grade Ammo, available here at Midsouth. For more information on this book, and others, plus articles and information for download, visit ZedikerPublishing.com