Bumping for awareness.
I had the same issues with my 300 PRC mags as others have shown in this thread. Rounds were nose diving at about a 50% rate. AI took about a month to do nothing other than send me a new mag. It would have been nice to actually talk to someone about the issue, or even tune the mag a little, instead of just sending a new mag and hoping the problem goes away. The new mag measured the same as my old one and predictably still had the nose dive issues. AI ignored me after I tried to tell them the new mag had the same issues. Total BS IMO.
On the other hand, Jason
@PerformanceWeapons had my mags turned around in less than 24 hours after getting them. Fan fucking tastic CS. I just put 120 rounds through three mags and had 100% reliability. The mags now feed just as good as 308 whether partial or full. Shame AI couldn't provide a fix, but just glad good guys like Jason are around to pick up the slack.
If you're having trouble with 300 PRC mags, definitely get in contact with Jason.