I took out my USC/UMP 9mm conversion today, and had some issues. On the last round of every magazine, the brass would not eject. Sometimes it would just be sitting on top of the empty mag, other times it got stuck under the bolt. 3 different types of ammo, with and without the suppressor, same problems. I'm leaning toward the a new extractor, but I've only put about 1k rounds through the gun.