been shooting the snot out of my new ar15 9mm pistol. Its a 4.5 inch gun. Its been a bit finiky from the git go. But I think I figured out one cure. It had no feed ramp to speak of. I had bullets diving out of the mag and hitting right below the small amount of forcing cone and stopping dead jamming the gun. So I went to work with a dremel and cut more of a ramp. It helped a lot but I still had stoppages. I started paying attention and first found that all the miss feeds were with pc coated bullets. It seemed to run about everything conventionally lubed fine. then I got looking even closer and found what was giving me the trouble was SOFT hp pc coated bullets. I did a batch of the same bullets in solid form pc coated out of an alloy close to ww and water dropped them out of the oven and ive ran over 500 rounds without a single miss feed. I think its a combo of the soft lead and the grabby quality of pc paint (for lack of better words) that just had to much friction to feed well without a good feed ramp. Lead has a natural lubricating quality that was just enough better to feed just fine even soft. I pulled my hair out before I sat and opened my eyes a bit. I tried 3 different buffer springs 3 different buffer weights and even blamed magazines and ended up finding that once I discovered this the original set up worked just fine and all my mags work just fine. then I got looking around on the net and found a company that sells a 9mm AR barrel with an actual feed ramp. Looked at his add and right in the add he said he didn't guarantee function with pc coated bullets so I'm probably not the first one that's discovered this.