August 5, 2021
Have you ever wondered what causes a bulge or mark on a case? What makes the case unfit for further use? Sierra Bullets Ballistic Technician Duane Sircks provides insight into various issues, and their causes, in two Case Diagnostic articles on the Sierra Blog.
Incipient Case Head SeparationThis Winchester.308 Win case has a real problem. This case is in the process to becoming a complete failure due to an incipient case-head separation.
This is usually caused by excessive headspace, which is common in cases that are over-sized. This case can be disassembled after a few firings, and then re-sizing. This case requires proper die adjustment. This case cannot be reused.
Excessive pressure (Load Too Hot).
You will see two pressure signs in the photo of the case rim. First, take a look at the primer. It is flattened to the maximum safety level. If this were the only pressure sign, I would likely be fine with this load. However, I would always keep an eye on it, especially if I was going use this load in warmer climates. This load could easily reach the “excessive pressure” realm very quickly.
Another sign of pressure is something we must not ignore. You’ll notice an obvious ejector mark that is located above the R-P headtamp. This clearly indicates that the load was not within the safe pressure range. These rounds should not be fired if they were loaded. This case should not ever be reloaded.
Split Case-Neck
This is an R-P.22-250 case, which has died. The case is in good condition, except for the split neck. This case should be thrown away.
Split neck is something you should be aware of. It is caused due to work-hardening. Brass cases become harder with age and usage. If a case is stored for too long, it can become so hard that it will split in two. I’ve seen factory loads do the exact same thing. These cases get more difficult as we resize them and fire them repeatedly. They will eventually split. Careful annealing can extend the life of a case. This issue would require an article. This case is not usable.
To help students understand what to look for in the classes I teach, I use examples such as this. As always, if we can assist you, whether you are new to reloading or very experienced, contact us here at Sierra Bullets by phone at 1-800-223-8799 or by email at [email protected].
Dented Case Body
Here is a Lake City 7.62×51 (.308 win.) Two marks/dents on the case body.
This one is a bit mysterious. This case could have been caught in action by a semi-auto rifle. The firearm jammed or the case failed during the cycling process. To avoid feeding problems, I wouldn’t reload the case. It also looked like a factory loaded case. I don’t see any damage or pressure issues.
Multiple Problems — Lake City 5.56×45 unknown Year.
This case has been through many failures and cannot possibly be re-used. It has a very rounded shoulder, which is split. It was obvious from the first glance that this round had been subject to excessive pressure. The firearm (or AR?) was damaged. The firearm (perhaps an AR) was not in full charge. The primer was extremely flat and the outer radius of the primer cup had been lost. High pressure! The ejector mark was also visible on the case rim. This is most likely an accident of excessive pressure. This case should be thrown out.
For more examples, see Part I and Part II of Sierra Bullets’ Case Diagnostics:
Before each reloading, it is important to inspect and inspect your cases. It becomes second nature to notice the small things after a while. As you get more familiar with the reloading process, don’t be complacent. Sierra’s Techs can be reached at 1-800-223-8799 if you have any questions.
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Tags: Bulged Cases. Case Diagnostics. Case Separation. Flattened Primer. Pressure Signs. Sierra Bullets. Split Case-Neck.
