Wrinkled brass from Marlin Camp 9

[commander faschisto]

Ok, here's a new one on me: I got a nice little Marlin Camp 9mm from my brother, which is totally fun to shoot. However, after lettin' fly with several rounds of Federal AE, I picked up a few cases, and noticed much to my surprise that every ejected case had three very consistent, smooth annular bulges along the case wall. Looks like someone put the case in a vise and partially collapsed the case wall like a rounded accordion bellows. What is up wit' dat?

Only happens during actual live firing cycle, can't get it to do it by hand releasing the bolt and letting it slam forward. I also tried installing the original 11lb recoil spring...same result as with the replacement 16lb spring. Has new buffer pad, too. I suspect oversize chamber? Any ideas would be appreciated, 'cause this is just such a fun little gun.

[Hoot]

Ok, here's a new one on me: I got a nice little Marlin Camp 9mm from my brother, which is totally fun to shoot. However, after lettin' fly with several rounds of Federal AE, I picked up a few cases, and noticed much to my surprise that every ejected case had three very consistent, smooth annular bulges along the case wall. Looks like someone put the case in a vise and partially collapsed the case wall like a rounded accordion bellows. What is up wit' dat?

Only happens during actual live firing cycle, can't get it to do it by hand releasing the bolt and letting it slam forward. I also tried installing the original 11lb recoil spring...same result as with the replacement 16lb spring. Has new buffer pad, too. I suspect oversize chamber? Any ideas would be appreciated, 'cause this is just such a fun little gun.

Put the rounds in by hand, with the magazine out of the rifle. Fire as many that way as you did before you got a wrinkled one. If none occur, get a different magazine.

Hoot

[commander faschisto]

Veddy good...I will try that tomorrow assuming I can withstand the 110F degree heat index...thanks for the suggestion! Hadn't thought about the magazine issue, which is always lurking in the background with box-feeds. I have a mix-n-match glom of various 20rd mags for this thing, and I might have to sort through them to get the gooden's, if this is the problem.