I've got an AP4, 308with about 100-120 rounds through it. I broke it in according to DPMS website. Last time it went to the range my son said it had 3 different types of jams. I thought maybe it was the second mag which was never used up to that point. I tryed it today and using the mag I always use, it had a failure to feed on the third bullet with only 5 rounds inserted in mag to begin with. The tip of the bullet got stuck on the bottom edge of the left hand feed ramp and was pushed into the case. I was using Remington factory 150 grain loads. I tried to re-create the jam by not pushing the bullets all the way back against the rear of the mag but I could not. I tried using each of the 3 mags I have and couldnt get another jam of any sort. What could possibly be the cause of a jam like this? I only shot slow fire, rapid not allowed on this range. Gun is meticulously cleaned and lubed after each range session. Any thoughts?
If you can't re-create the problem, it could be something with that particular batch of ammo (unless you were using multiple kinds of ammo). Maybe some imperfection on the end of the bullet is sticking to another imperfection somewhere on the feed ramp.
You could always polish up the feed ramps to smooth out any possible burr.
