I was an aircraft maintainer for twenty years in the Air Force. I qualified on the M-16 and the shotgun for many years. I'm not sure there was an "expert" score with the shotgun, although I loved firing it...loud and lots of recoil! I never had a problem with the M-16 except for the fact that I tended to shoot the adjacent target!!!! My last time on the range with that weapon, my best friend was in the next lane. We fired 100 total rounds. I had 80 rounds in my target. He had 120!!! My last assignment (Pope AFB in 1992-95), I was the section chief. I've always loved revolvers and my training NCO knew that. He asked if I'd like to qualify on the revolver. I jumped at the chance, knowing that the M9 had already became the standard sidearm and the revolver would soon be going away. The only thing I recall about the course of fire was that it was all double-action and was at 25 yards. I smoked it! Finally got my expert ribbon.