Tag Archives: case necks

RELOADERS CORNER: 4 Firings In

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Along with all the other operations we do to them, cartridge cases also need maintenance. A good question is “when”? That’s next… KEEP READING

old case

Glen Zediker

I tend to write much of what I do for those who reload for production. Those are folks expecting good utility in exchange for the expense and effort: a reliably-performing round of ammunition, over and over again. They’re loading and reloading because they like to shoot. It’s a big bonus to most, and I include myself in this group most of the time, if that good performance comes with a minimum of effort. Clean, size, prime, fill, seat, shoot. Five steps to get to the one thing that matters most: shoot! I am also in another group some of the time, not as often now as I once was, and those folks may add a few more steps before getting to the “shoot” part (case prep mostly).

It would be wonderful if that simple cycle endured without end. But it won’t.

Overall case condition after X-many firings varies A LOT because of a lot of factors, variables. What matters is getting a handle on it. I look over each case each time I load it, but I don’t break out the measuring tools. That’s not neglect. There is never (ever) any excuse for neglect. That’s not what this is about. It’s about working out a responsible, reasonable, and realistic schedule for when to take a close look at the progress in condition that new batch of cartridges cases has followed after some time.

In my experience, which is what’s in my notes, I say that’s 4 firings.

I went through the per-use checks enough times to know the schedule one brand and lot of brass, used with the same loads in the same barrel, follows with respect to changes. And by that I mean when changes require attention. I’m also starting with prepped cases, including trimming, before their first firing.

Let me make clear that I’m not suggesting that 4 firings is maximum case life! What I am suggesting is that this is the point where it’s likely to see measurable influences from use and reuse, and, as such, that it can be measured. That’s what we’re after now: take a check to see what’s happening, and that also is a big help toward getting clues about where and when these changes might get noticeably influential.

So, to be clear: the case has been fired four times, reused three times. Next loading, if there will be one, will be for the fifth use.

chamber reamer
We, or more correctly, our cases, are at the mercy of this thing: a chamber reamer. It sets the amount of space the case can expand into.

Changes
Continuing to use and reuse cases, we’re not really using the same cases each time. The cases change, and much of the change comes from material flow, which is brass.

Here’s how it goes, which is to say here’s how it flows: Case neck walls get thicker. The case head area body walls get thinner, over a short span of the body. Primer pockets get shallower and larger diameter. Overall, the alloy hardens over the whole case.

As gone on about a few times in this spot, there’s going to be more change in cases run through a semi-auto than those used in a bolt-action. That’s because of the necessarily additional (comparatively speaking) sizing and also the additional stress resulting from the firing cycle. There’s more flow because the cases are free to expand more.

drop bullet
A simple, and important, test to check if case necks walls have thickened excessively is to take a fired case and drop a bullet in it. If it won’t drop without resistance, stop! That’s way too much.

The Neck
All case necks expand to whatever the chamber allows. There’s no relationship between that and sized dimension because, clearly, there has to be a small enough neck inside diameter to retain the bullet. It is, though, one of the reasons case necks tend to give up quickest (plus it’s the thinnest-walled area on a case).

The case neck is my primary concern, and the first thing I check. If the walls get too thick it’s possible to cut the space too close between the case neck and the case neck area in the rifle chamber. There might be interference upon bullet release, and that creates excessive pressure, or sure can. All that depends on what the chamber allows for expansion room.

The most simple check is to see if a bullet will freely drop into a fired case neck. If it won’t, stop! Do not reuse that case as-is. A case that won’t pass this no-tool test has excessively thickened.

Somewhere in your notes should be a figure indicating loaded outside case neck diameter, on new brass. This dimension is exclusive of the sized neck diameter, because when the bullet is seated the neck is going to expand to accommodate the bullet. Another check of loaded outside neck diameter will show if there’s been thickening. If an inside neck sizing appliance is used (a sizing button), then that will tell you also, comparing it to what you also recorded for the new case after sizing it. (And it’s a good reason to always run new brass through your sizing die, even if it’s “ready to go” out of the box.)

I hope it’s clear enough why it’s important to “write everything down.” References, standards are big helps.

Direct checks of the neck walls themselves using a suitable tool will show thickening. However! Case necks don’t necessarily thicken the same over the entire height of the case neck cylinder. Remember, the brass is flowing so moves in a direction, and that part of the case has a wave going forward, toward the muzzle. There can and likely will be a tapering from thicker to thinner. Measure at more than one point.

Safety is one thing, and the most important thing, and then the other thing is accuracy. Case neck “tension” needs to be consistent from loading to loading to get reliable accuracy.

Fixing it? An inside case neck reamer is the easiest and most direct means. However! Make double-dang sure you know the numbers and therefore how and at what point to use it! Many are intended for use on fired (not yet resized) necks. Others are a specific dimension that you may or may not be able to specify. Thinning the case neck walls using an outside case neck turner is another direct remedy. A little tedious.

forster reamer
The best way I know to remove material to refurbish overly-thickened case neck walls is an inside case neck reamer. This is a Forster, designed to work with their case trimming base. Trick is knowing the case condition it was designed to be used with. This one is dimensioned for use on fired, unsized case necks (it’s 0.003 under bullet diameter). Run it on a sized neck and way too much brass comes off. Various sizes are available.

Reamer or turner, though, this job hasn’t finished until the refurbished case has been run through your usual sizing die, and checked again for diameter.

Well, so much for this here and now. Out of room! More next time…

See REAMERS HERE

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

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

par15

RELOADERS CORNER: Inside Reaming Vs. Outside Turning

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Some confuse these operations. Don’t! Here’s what each is, and isn’t…

Glen Zediker

I get a lot of questions. I always answer each one, and in doing so that experience reminds me of the wide span of topic knowledge needed to be a successful, and safe, handloader. I make an effort not to assume any level or depth of anyone’s understanding of any topic I might address. At the risk of “offending” all the experts out there by wasting their time with fundamental starts to technical pieces, I’d dang sho rather bore them than shortchange a newcomer out of elemental information.

I told folks in my last book that “grains” refers to a propellant weight, not a kernel-count. Right. But I’ve fielded that question more than once. That’s not, in my mind, a “stupid” question. Truth: The only stupid question is one that’s not asked, when there’s a need to know.

So, that was leading into this: Here’s a question I got just yesterday that sourced via someone who wasn’t even a little bit uneducated in the need for finer points of case prep. This fellow was confused about the relationship between inside case neck reaming and outside case neck turning. Here’s a longer version of the answer I returned to him —

First, there is no relationship between inside neck reaming and outside neck turning, and by that I mean they are not a combined process. As a matter of fact, these should not be combined!

They can be confused because they both ultimately accomplish the same thing, the same basic thing: each process removes material from a cartridge case neck cylinder, and that makes the case neck wall thinner. These two ops, however, are done for two different reasons.

neck reamer
Inside neck reaming is a treatment to thin excessively thickened case necks after several firings. If the neck walls get too thick, the outside diameter of the case neck might not have adequate room in the chamber to expand to release the bullet. Excess pressure! Shown is a Forster-brand accessory for its case trimmer.
IMPORTANT: “Standard” case neck reamers are for use only on fired but not resized cases! Exceptions are custom-size reamers, and I own a few of those that get use from time to time, but, as was said for tight-necked rifles, if you know about that then you already know about this…

An inside case neck reamer is intended to relieve excess material from case necks that have thickened excessively through use and reuse. Brass flows, and it flows forward.

Important! Most “standard” case neck reamers are intended to be used on fired, but not yet resized, cases! In other words: Use the reamer on the fired cases as-are. Do not use one on a case that’s had its neck resized because that will cut away way too much brass.

Another application where inside reaming is frequently recommended is in forming operations that require a reduction in case neck diameter. When a case is “necked down,” which means run through a sizing op that creates a .243 caliber from a previously .308 caliber, for instance, the neck walls thicken. An appropriately-sized reamer makes the shortest work of this tedious but necessary job. Most forming die packages either include or make mention of the specific-size reamer to use.

Outside case neck turning is done to improve the consistency of case neck wall thickness around the cylinder. It’s a step taken to improve accuracy. Outside case neck turning should be done only on brand new (unfired) brass. It’s more precisely effective and easier because that’s when the alloy is at its softest.

turned case neck
Outside neck turning is a “precision” case prep step that improves consistency of the case neck wall thicknesses. It can be done a little bit to clean up “high spots” and make the cases better, or full-area to make them nearly perfect. That, of course, also makes them universally thinner so your sizing apparatus might need to be dimensioned differently to maintain desired case neck inside diameter to retain adequate grip on the bullet.

There are specific, custom combinations that require a smaller than standard case neck outside diameter. The “tight-necked” rifle, which is just about exclusively encountered in Benchrest competition, has to have its brass modified to chamber in the rifle. The neck area of the rifle chamber is cut extra-small to provide a means to attain a “perfect” fit and minimal case neck expansion. If you’re into this, then you already knew that…

So, the primary role and use of an inside neck reamer is as a safety precaution; its secondary use is as a prep step in case forming. The primary role and use of an outside neck turner is to improve the consistency, quality, of a case neck cylinder. The idea is that more consistent wall thickness leads to a more centered case neck. And it does. Reaming does zero to improve consistency. Reaming just makes a bigger hole of the hole that’s already there; it doesn’t relocate its center.

drop test
The way (or one way) to tell if your cases need a ream is to take a fired case and see if a bullet will freely drop through the neck. If it won’t, they’re too thick. Thrown them away or refurbish them with a reamer. Resizing won’t change a thing.

Combining these ops might create a safety issue because the necks might get too thin, and that could mean there wouldn’t be enough grip on the bullet. Point is, ultimately, that reaming and turning are not equivalent even though they might seem to be doing the same thing. One is not a substitute for the other. It certainly would be possible to remove metal from the outside of the neck cylinder to overcome the effects of thickened necks, if (and only if) the neck is sized again using the usual die apparatus. When that’s the goal, though, a reamer is lower effort, faster, and less expensive to buy into.

Very important! Always (always) culminate either operation by running the cases a trip through the sizing die you normally use.

Check out a few tools at Midsouth HERE