Cartridge dissection - Open to interpretation

[Lefty7mmstw]

I used to dremmel one in half for gits and shiggles once in a while... Today's brass prices dictate that I wait for the separation line and toss 'em in the scrap when they get that... I don't bother with the bent feeler anymore either with my 7stw brass; it doesn't have a sharp thinning and the feeler doesn't catch it... I will use a feeler on some of my other brass if there's a question but usually the line will show up..

 

[GLTaylor]

The RCBS concentricity gauge also comes with a small arm you can run in and out of your cases. It has a sharp hook on the end to feel for incipient case separations. In addition, you can use the dial indicator to measure wall thickness if you like

 

[scott0303]

It looks like the neck needs to be squared up.

But seriously, I admire the curiosity that spurned this exercise. Just today, I was evaluating some .25-06 cases for wear and was using a bent paper clip as a feeler to detect that crease that develops as a blurry line on the outside and upon subsequent firings becomes more distinctive. I'd like to see what that looks like from the inside.

 

[cohunt]

Scott, u Definately got some wall thinning going on near the web, how much are you bumping the shoulder when you resize ?

 

[hunter0528]

The things that stood out to me.

Along the web, you can see the striations. To me that looks like where the case gets worked the most.

The white by shoulder and neck, I believe it looks like that due to the annealing process. Or because of the bottle neck created. Still pondering that.

The carbon fouling seems to get thicker and blacker from the base to the neck. To me that speaks to how the powder ignites, burning faster and hotter. Makes we wonder if I uniform the flash holes I will get a better more even ignition.

Lastly, corn cob media cleans the outside great but not the inside... wonder if a wet tumbler or sonic cleaner would do better.

The ultrasonic cleaner (if you decap first) cleans everything inside outside and primer pockets.

 

[MNbogboy]

Great pictures of impending problems.

Cohunt is right on here. The thinned area is a product of excessive case stretching. Minimal shoulder bumping will prevent this in your next batch. Cases should fail for other reasons before this type of failure.
The infamous "paper clip" test will help to detect this problem before full case failure but only proper die/chamber headspace setup will prevent it.