My buddy shagged a P3AT and we found it had failure to feed problems with Winchester UMC FMJ rounds. I polished the ramp and bore but the problems still existed. The second time in I noticed a hang up point while feeding a round with the barrel out of the gun at the junction of the feed ramp and the bore when I pushed it in at the same angle that the slide feeds the round. The bullet seemed to hang at the point the bullet head met the case at the ramp / bore area. I carefully rounded that area of the barrel knowing that if too much metal is taken off it could be a dangerous condition. The case is not supported if too much metal is removed and it could split and blow the magazine out and hurt your hand. I have seen this happen. I repeat, not much metal was removed, just rounded off a bit. This seemed to do the trick and the gun began feeding normally. Here is a picture of the area in question.