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Complications of Cartridge Case Life

When it comes to case life, too many variables preclude anyone from quoting specific numbers. So the rule is always inspect!

Complications of Cartridge Case Life

The dark ring around the firing pin hole of this Colt Government Model is eroded metal caused by loose primer pockets in cases that were reloaded well past their “best by” date. (Photo courtesy of Allan Jones)

My editor recently received a letter asking about cartridge case life. It was a great question, but it opened a Pandora’s box of ballistics issues involving firearm condition, case types and metallurgy, pressures, and more. This is akin to asking your mechanic, “How long will my car last?”

I have some .38 Special cases from 1969 fired exclusively with light target loads; they are still serviceable after logging 20+ firings. In the lab, I’ve had belted rifle cases become questionable for continued use after one firing. Case life is a concern specific to handloaders; if you shoot factory ammo, this point is moot.

In bottleneck rifle cases, survivability depends primarily on case wall stretching ahead of the case web that is affected by headspacing. These cases should be monitored for stretching after every firing. A straightened paper clip with a short 90-degree bend at the end can probe the case interior near the head. Serious stretching means you can feel a “dip” in the case wall, often in the presence of a bright ring of brass at the corresponding point on the outside of the case.

To establish a feel for what is “too much,” you may need to cut open a case or two at first to help visualize how much “dip” is present. You can measure this in an intact case with an RCBS CaseMaster Gauging tool. My personal opinion is this: Any case that has lost 20 to 25 percent of its thickness at that point is “running on fumes.”


Most handgun cases experience lower pressures and don’t rely on a shoulder for headspace control; stretch is seldom a concern at even .44 Magnum pressures. Headspace issues in handguns usually manifest as accuracy problems, not case failures.


Incipient or total case head separations, blown primers, and split necks are as obvious as a pig in the punchbowl, but there are some harder-to-spot case issues.

Constant firing even at comfortable pressures can wear out cases. I started shooting .45 ACP in IPSC/USPSA competition in the 1970s with 1,000 once-fired military cases with the same headstamp. I’d always heard you’ll lose a semiauto case before you wear it out. Not this time. I repeatedly fired them with the same competition load for years. I later determined that load averaged 19,100 psi, a comfortable 91 percent of maximum average pressure (MAP).

I discovered the case aging while at the loading bench. I first noticed that some cases required less primer seating force than typical for that batch. Then a new issue arose. After seating bullets, I found high primers that were not high before bulletseating. Trapped air, compressed by bulletseating, partially ejected the primers. In the classic sense of the word, none of these cases failed, but rather, they “grew tired.” Did they cause gun damage? Yes, they did.

While cleaning my Government Model, I found a ring of frosted metal on the breechface surrounding the firing pin hole. The damage was cosmetic, not functional, but it was not there when I purchased the pistol.




Loose pockets allowed hot gas to leak, eventually etching the breechface. Constant safe pressures against the head of the case will gradually enlarge primer pockets after many firings. Those cases had given their all, and I scrapped the entire batch.

Rim burrs on semiauto cases result from extractor and ejector contact and are common after a lot of firings. They can cause slow feeding, inconsistent ejection, or outright stoppages. Feel for such odd effects like these between loadings. Yes, they can be sanded off, but badly nicked rims will affect insertion and proper positioning in a press’s shellholder or shellplate. If wear or damage in a sizing die produces shallow gouges in the case walls, that can eventually compromise a case.

Too many variables preclude anyone from quoting specific case life numbers, so the rule is “always inspect!” Even with the same cartridge, load, and reloading dies, two firearms of the same make may demonstrate differing case life.

Recommended


Case inspection must be Job One in handloading. Hone your instincts and trust your senses. Your eyes gather the most information. Your touch can detect burrs and bulges. Your hearing can detect badly split cases. A split case will have a tinny sound as it bumps other cases. Run your hands through the bin of cases, listening for “off” sounds. Rifle cases may need a length check. If firing allows excess brass flow, bullet pulls—the force needed to release a bullet from the case—becomes inconsistent.

Remember, a “tired” case is close to a failed case. This is where a good visual check of the case head before depriming is effective in finding those needing retirement. 

I run a finger over the head to check for rim or head deformation. Soot at the perimeter of the primer is a sign of problems. Is the primer cup “nail-headed” into the pocket’s radiused edge? Usually indicative of too much pressure, nail-heading or soot can also indicate a loose primer pocket.

If the headstamp is hard to read or looks shallow compared to a new case of the same make, that case is very tired. Enlarged primer pockets are not as easy to spot and require gauging a clean hole. However, for hobby reloading, the condition of the headstamp is a good clue to the condition of the pocket.

So what do I do? I fire nonbelted bottleneck rifle cases twice with full-power loads and then use them for practice or load testing. I check magnum handgun cases and those fired in semiautos for “flattened” headstamps. If the cases had been heavily crimped to secure a bullet, I watch for short mouth splits. I do the “sound” test 

I mentioned to find cases with bigger splits. 

I don’t obsess, but I do pay attention.

In times of shortages, like the one we have now, we may be tempted to get “just one more shot” from a cartridge case. For your safety and that of your favorite firearm, avoid temptation and don’t change how you judge case condition based on empty store shelves.

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