While processing some brass from a recent range outing, I came across some 9mm that was quite interesting. It was fired from a friend's pistol - either his Beretta Storm, or his H&K something (I don't remember the model number).

The case mouth is the diameter I would expect to see. About 0.200" from the case mouth, there is a slight shoulder. It's not as severe as a 357 Sig, but it is noticeable - maybe 0.010" to 0.020" worth of bulge. It's looks like what you might see if you wildcat'd a 45ACP to use a 44 cal bullet. It's not much, but it is visible.

(I resized all of them - I didn't think to measure. Sorry.)

I'm thinking it is one of a couple things:

1. The chamber reamer is slightly over sized to allow for grinding.
2. The chamber was designed like that to facilitate reliable feeding.
3. The new guy cut a bad chamber and they kluged it to make it work.

I doubt case 3 considering that both makers have good reputations for producing quality stuff.

Has anyone else seen this in a pistol?