Tag Archives: primer pocket uniforming

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 perfect 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: Accuracy 2

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Accuracy matters! Now here’s what matters to accuracy… This article discusses 5 essential steps that pay off big.

Glen Zediker

Last time I wrote a little “essay” on the importance of accuracy and a few ideas on why it matters and how to judge it. That’s all well and good, but the part I knowingly left out was to say more about “how” to get the most of it. Here’s a few points that, over a many-many years, have proven themselves to me to improve the quality of on-target perforations, and, to make sure I’m clear, that is manifested by smaller-diameter shot groups. There are a plenty of others who agree with these tips. There are plenty of others who might not agree with all of it, and even a few more who would love to add their own “can’t miss” components to this mix. But here are mine.

concentricity

ONE: After-the-fact concentricity. By that I mean actually checking loaded rounds on a runout indicator. Concentricity is pretty much the goal for sizing, seating, and neck-related case-prep steps, like outside case neck turning. However! All those things are done to help support concentricity, but not a one of them is concentricity.

Concentricty is the centered relationship of all influential circles in a cartridge case, with the reason that a more concentric round will have its bullet looking down dead center into the rifle bore: ultimately, if the loaded round spins “flat-line” it will shoot better than those that don’t.

It starts with brass selection and then likely also segregation. Then it moves on to the quality of tool alignment.

I have checked enough factory-loaded rounds though a concentricity fixture, and those that show the best group the best; even if the overall group from random selections is so-so, “flatliners” shoot smaller.

Check out Midsouth products HERE

TWO: Inside flash hole deburring. I know I’ve mentioned this before, but this simple and easy step shows up on target next firing on thusly-prepped cases. It improves propellant ignition consistency and, depending on the tool used, also ignition efficiency.

Inside deburring tool
How and why an inside flash hole deburring tool works is pretty clear to see. Despite the fears I’ve heard, it will not hurt the integrity of the case.

There’s a burr inside most cases that resulted from manufacture (with only a few drill-cut exceptions, like Lapua, cartridge case manufacturers punch the flash hole). This burr is variable in size and scope, but it acts as a block to the spread of primer flash, and it’s redirecting or misdirecting the flash at the same time.

It only has to be done once. Ever.

Check out Midsouth products HERE

THREE: Primer pocket uniforming. This helps because it lets you set each primer the same, and also fully. The reason is that it squares the “edges” or corners of what otherwise is a slightly bowl-shaped cylinder. A perfectly seated primer is sitting square and flush on the bottom of the pocket, with its anvil legs compressed. This “loads” the compound for rapid and consistent ignition. If the primer isn’t seated fully then the firing pin finishes that job before detonation. That creates what equate to time variables — inefficiency.

Funny, but clean primer pockets don’t shoot any better than dirty pockets. What matters is flat pockets.

Check out Midsouth products HERE

FOUR: Consistent case sizing. There is a widespread fear, especially among some “accuracy” fanatics, about sizing ops. There’s also a lot misunderstood about full-length sizing versus neck-only sizing and so on. But. What matters is that, whichever tooling and how much sizing the cases are treated to, it needs to produce dead-same cases. Consistent case expansion dynamics is not often talked about, but it’s influential, especially on longer-range rounds. Just in general, going a little on the “light” side with sizing might seem like a good idea (less stress, less working the metal, etc.) but it can also lead to round-to-round inconsistencies. My belief is that it’s better to be more “positive” in sizing ops, and by that I mean to reduce a case neck 0.003 inches rather than 0.001 prior to seating a bullet. Get all the case shoulders the same height. Running extra-light case neck tension and leaving case shoulders where they emerged last firing may not reproduce round-to-round consistency, unless the rifle chamber was perfect and the cases were too. A little more sizing works the best for the most of us in the most rifles.

Forster seating die

FIVE: Invest in a good seating die. No doubt: the bullet seating operation is the “last thing” that happens and it’s also the one thing that can corrupt the care and treatment given to the quality of the loaded round prior. A sleeve-style seater, well machined, goes a whopping long ways toward preserving alignment, and, therefore, concentricity. Also make sure that the stem in yours comes to rest well down onto the bullet ogive, and, above all else, is not contacting the bullet tip! That will wreck a round.

seating stem
Remove the seating stem and drop a bullet into it. The farther down the ogive or nosecone the step recess grips the bullet, the better. If it’s only pressing down against the bullet tip, a crooked seat is assured, along with inconsistent seating depth.

Check out Midsouth products HERE

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