After a shell is ejected, the new round gets stuck as it enters the barrel in between the barrel and the bolt. Attached is a pic of the jam, along with the bottom of the bolt. It seems as though this happens quite a bit, but mostly at the start of a new magazine (I'm assuming because the magazine spring is pushing the round up harder). It's easy to clear, just have to pull the carrier back slightly until the round pops up in front of the bolt. I'm not sure what's causing this...any suggestions? It's an American made receiver, Sierra Arms.