extreme pressure?

[RMiller]

While going thru some used 6BR Lapua brass I picked up I found 3 cases with bulged primer pockets. Not expanded but bulged.
I've expanded a pocket once or twice but never have I had one look like the picture below. The pocket wasnt lose and the case looked in good condition in every other way.
If it was high presure wouldnt the pocket have expanded?
I have no idea what the load was or what the primer looked like.

To be honest, after looking at this case im surprized it dosent happen more often instead of the pocket opening up.
Makes me think about whats really happening if you are running a primer pocket tool in your case after every fire. If the bottom of the pocket can be blown forward and everytime you clean your pocket youd be removing a little of the bottom of the pocket till it was real thin. Youd never see it.

Anyway, Thought it was interesting.

 

[kitsap]

At first look it appears the case was damaged by contact with a de-capping rod assembly. Either as part of a resizing die or a stand alone de-capping die. The die was not properly adjusted and the rod made contact with the inside base of the case. It happens at the top of the stroke of the press ram and the user seldom notices.

DougF

 

[RMiller]

Hmmmm, that sounds logical.
I was having a hard time thinking it was a pressure issue.

 

[Preacher]

Pretty sure thats exactly what caused the problem, I noticed one time while setting up a new NJ die that the primers were not seating all the way in... Sure enough the decapper was to low and it was hitting hard enough that it was belling the primer seat... A bit of adjustment and the problem went away.. Never did feel the difference either...

 

[queen_stick]

Never seen anything like that before. I'm glad you posted this, so I know to watch out for it.

I'm curious if tried firing any of these cases. If so, did you notice a difference in accuracy?

Maybe you've discovered the trick to shooting one ragged hole at 1000 yards!

 

[RMiller]

I had never seen this before my self and you can bet I will keep my eye on it from now on. I cant imagine decapping a full box of brass only to find out afterward that they are now all ruined.

As far as shooting them, no I didnt and you really couldnt shoot them. The primer cant be seated all the way in the pocket. As a matter of fact while I was looking at the case I tryed to prime it to see if they had been expanded and had a hell of a time getting it out of my auto primer. If the primer isnt seated all the way it wont slip out of the holder. I had to fource it in the the case just to get it out. Was a mistake on my part to try it.

As far as bug holes at a 1000, unfortunatly Im still searching for the magic combination.

 

[SmokinJoe]

Actually, you could probably cut the dome down with a primer pocket uniformer, but that would be an awful lot of work. I would just chalk it up to experience & throw that brass away.

 

[queen_stick]

I don't blame you for trying to seat a primer in there. I probably would have tried the same thing, and also got the case stuck in the priming tool. Now I know not to try that either! I still find it amazing how many little details go into reloading. If you miss one little thing, like having the decapping pin set a tad long, you run into all kinds of problems. Like smokinjoe said, it's good experience to run into these things, so you don't repeat it in the future. That's typically how I learn... the hard way.