AR 308 feeding problem

[jsc8041]

Just finished an AR 308 build, took it out to fire and it would not extract properly. i found the extractor had ripped a chunk of the rim on each case, so i chalked it up to bad ammo. with slightly better ammo, the rifle ejected every round successfully, however roughly 80% of the time, the bolt would close, but without stripping off the next round in the magazine. with the bolt pulled open, i noticed the same marking on the top round in the mag, single line along the length of the cartridge, probably from one of the bolt lugs.

any ideas on what part of the rifle is causing this issue? thanks for your time.

[bjl333]

did you try a different magazine? Sometimes the mag don't push the next round up.

[junko p]

did you use the correct .308 weighted buffer and spring? What kind of stock? If it is ripping off part of the rim it sounds like the extractor/bolt has too much energy on its way back. Not an expert, but that would be my first guess.