ANY CLUES?

[dilligaf]

Ok so I completed an AR build in 6.5 CM back in March and am now just got around to shooting it. It has an Aero Precision 22" upper and Ground Zero Precision BCG in an 80% hand finished lower rcvr. The problem is, see pics: I have had a few jams that have severely damaged the cases to the extent of bending and creasing. I have never seen anything like it. Wondering if anyone else has come across this? I can't determine if it could be extractor issue, mag issue or buffer spring. I am using AR Stoner steel mags and Pmags for 308. I did do a dry run by cycling the bolt with some ammo in both mags and found a round didn't extract and one in the mag trying to go under or around the one in the chamber so I am leaning toward extractor but could there be other issues? It doesn't do it on every round either. I would fire 2 or 3 consecutive rounds then it would happen, same with cycling rounds by hand. When it does fire btw, it shoots very nice groups.

[BrianR.]

Seen it occur with my department steel mags that were used for trainings. Just never figured out what caused it because it was a sporadic issue. Mags were also immediately taken out of service.

[MD66948]

Are you using the same magazine?

[dilligaf]

Are you using the same magazine?

Tried steel AR Stoner mag and Magpul PMag. The steel was live fired (the pics) and the PMag was hand cycled with live rounds. it seems it will cycle a couple times then jam. Note: All mags are new as is firearm parts.

[Jhaydeno]

Could be a mag, doubtful with a p-mag, but you did hand finish the lower, so check the mag catch placement (height of feed lips to high or low).

Could be the extractor - not enough gap between the extractor and the bolt face so there’s not space for the rim to engage. Make sure the extractor is not binding in the BCG too.

Mic your barrel chamber too (or hand run a bunch of ammo), it could be tight and need some polish.

Just my $.02