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September 20th, 2023

Inspect Your Brass To Detect Case Failure Warning Signs

Glen Zediker reloaders corner midsouth book AR-16 reloading semi-auto brass safety primer resizing
Close-up view of a sectioned case. This one here was “fixin’ to pop”, observed Glen Zediker.

Here are highlights from an article Glen Zediker wrote for the Midsouth Blog. In that article Glen, who sadly passed away in 2020, focused on cartridge brass. Glen identified the most common failures that appear with brass that has been shot multiple times, or which has been fired at excessive pressures. Glen explained some simple ways to check your cartridge brass to detect “early warning signs” of case failure, particularly case head separation, which can be very dangerous.

Glen authored many excellent books on reloading. This article is adapted from two of Glen’s books: Handloading For Competition and Top-Grade Ammo.

How Cases Degrade with Multiple Firings By Glen Zediker
This article explains when, and then how, to check after the progress of changes commencing with the firing on a new case. It’s the “progress of degeneration,” in a way of looking at it because the concern is getting a handle on when enough change in the brass has come about to require attention. Or abandonment. As said then, for me that’s 4 firings. That, as said last time, is when I might see changes that need attention. Also as said, that figure didn’t come out of a hat, but from my own notes in running my competition NRA High Power Rifle loads. [Editor’s Note: With Lapua brass, using moderate loads, in bolt-action rifles, we typically get about 10 good (match-worthy) firings. But if you anneal your Lapua brass, and run modest pressures, Lapua brass can perform well for 20 or more load cycles.]

The areas most affected are the case neck and case head area. Case neck walls get thicker [but] the case head area body walls get thinner. Primer pockets get shallower and larger diameter.

Glen Zediker reloaders corner midsouth book AR-16 reloading semi-auto brass safety primer resizing

This case shows a cracked neck AND a crack (separation) above the case head. Zediker says it is “rare to see one case with both of the most common failures. [This case] was attacked by an M14.”

Case Head — Causes of Separation and Cracking
When a case is under pressure during firing, the brass, like water, flows where it can, where it’s more free to move. Of course, the chamber steel limits the amount it can expand. The case shoulder blows fully forward and the case base is slammed back against the bolt face. There is, therefore and in effect, a tug on both ends — it gets stretched. The shoulder area is relatively free to expand to conform to the chamber, but the other end, the case head area, is not. Since that’s the area of the case with the thickest walls, it doesn’t expand “out” much at all. What it does is stretch. The “case head area,” as I refer to it here, is the portion of the case above the web, which is just above the taper that leads in to the extractor groove. The “area” extends approximately an eighth-inch up the case body.

Glen Zediker reloaders corner midsouth book AR-16 reloading semi-auto brass safety primer resizing

Here’s a “pressure ring.” You’ll see this after firing, if you see it. And, if you see it, that case is done. The bright ring indicates excessive stretching, which indicates excessive thinning. If you see a ring circling the case, noticeable because it’s lighter color than the case body, and it’s in this area, I’d say that case is done. And that’s right where a “head separation” occurs. It can crack and also blow slap in two, and that’s the “separation” part of case head separation.

Case-head case cartridge pressure ring separation head failure GS Arizona
Photo courtesy GS Arizona.

This is a spot to keep close watch on as cases age. It is also the area that is more “protected” by sizing with less case shoulder set-back. That is, pretty much, where the freedom for the stretching movement in this area comes from (the case shoulder creates a gap). If you’re seeing a sign that a head separation [might happen with relatively few firings], chances are the shoulder set-back is excessive, and also… the load pressure level.

Bent Paper Clip Case-Wall Gauge
Case-Head Separation paper clip Glen Zediker GS Arizona

Editor: You can use a bent paper clip to detect potential case wall problems. Slide the paper clip inside your case to check for thin spots. GS Arizona explains: “This simple little tool (bent paper clip) will let you check the inside of cases before you reload them. The thin spot will be immediately apparent as you run the clip up the inside of the case. If you’re seeing a shiny line on the outside and the clip is really hitting a thin spot inside, it’s time to retire the case.” Photo by GS Arizona.

Monitor Primer Pocket Dimensional Changes
Another case-head-area and pressure-related check is the primer pocket. As said, the primer pocket will get larger in diameter and shallower in depth each firing. As with many such things, the questions are “when” and “how much,” and the main thing, “how much?”

If the pocket gets excessively shallow, and that’s judged by a primer that seats fully but isn’t at least a tick below flush with the case base, there could be function issues. There’s a risk of a “slam-fire” with a semi-auto that uses a floating firing pin, and, if there is actual protrusion, that has the same effect as insufficient headspace. A primer pocket uniformer can reset the depth of a shallowed primer pocket to what it should be, but the real test for me is how easily the next primer seats into it. If it’s significantly less resistance, I’ll say that case is done. Shallower can be refurbished. That’s a primary function of a primer pocket uniformer. Larger diameter, though, can’t be fixed. I’ve mentioned in another article or two that, any more at least, my main gauge of load pressure has become how much primer pocket expansion there’s been.

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip No Comments »
July 9th, 2022

Handy Small Magnifiers Are Great for Many Handloading Tasks

Magnifying lens LED light relaoding

pocket fold-out magnifierWhat is the most-used piece of equipment on this Editor’s reloading bench? No it’s not my Rock-Chucker press, my priming tool, or even my calipers. The one item in near-constant use is a small, folding magnifying glass. Mine folds into a square case and offers 4X viewing with an 8X bifocal insert. With this handy tool I can inspect case mouths for burrs, check primer pockets, inspect meplats, and look for flaws on bullet jackets. I also use the magnifier to see rifling marks on bullets seated into the rifling, or check my bolt for galling. The number of uses is nearly endless. I keep one magnifier at my reloading bench and another in my range kit.

Folding magnifiers are so handy yet inexpensive that you should own a couple spares (including one in the range box). I bought my magnifier in a book-store, but you can also find them on Amazon.com and FoldingMagnifier.com starting at under $2.00. To see inside cases and dies and view fine details, consider the 5X Meromore Folding Magnifier with a built-in, battery-powered LED light, plus a 11X high-magnification insert.

With a decent small magnifier, you can easily see any minute flaws in your barrel crowns. That’s important because crown damage can cause hard-to-diagnose accuracy issues. We’ve known guys who spend weeks tinkering with loads, when the real problem was a worn-out or damaged crown.

The slide-out iLumen8, shown at left in top photo, offers 3X power with built-in illumination. An “Amazon’s Choice” item, this palm-sized magnifier is $20.75 on Amazon.

Permalink Optics, Reloading, Tech Tip No Comments »
July 5th, 2021

Handy Pocket Magnifiers Help with Many Reloading Tasks

Magnifying lens LED light relaoding

pocket fold-out magnifierWhat is the most-used piece of equipment on this Editor’s reloading bench? No it’s not my Rock-Chucker press, my priming tool, or even my calipers. The one item in near-constant use is a small, folding magnifying glass. Mine folds into a square case and offers 4X viewing with an 8X bifocal insert. With this handy tool I can inspect case mouths for burrs, check primer pockets, inspect meplats, and look for flaws on bullet jackets. I also use the magnifier to see rifling marks on bullets seated into the rifling, or check my bolt for galling. The number of uses is nearly endless. I keep one magnifier at my reloading bench and another in my range kit.

Folding magnifiers are so handy yet inexpensive that you should own a couple spares (including one in the range box). I bought my magnifier in a book-store, but you can also find them on Amazon.com and FoldingMagnifier.com starting at under $2.00. To see inside cases and dies and view fine details, consider the 5X Meromore Folding Magnifier with a built-in, battery-powered LED light, plus a 11X high-magnification insert.

With a decent small magnifier, you can easily see any minute flaws in your barrel crowns. That’s important because crown damage can cause hard-to-diagnose accuracy issues. We’ve known guys who spend weeks tinkering with loads, when the real problem was a worn-out or damaged crown.

The slide-out iLumen8, shown at left in top photo, offers 3X power with built-in illumination. An “Amazon’s Choice” item, this palm-sized magnifier is $18.95 on Amazon.

Permalink Gear Review, Optics, Reloading No Comments »