Not since 1945, Jeff. I know. I pulled triggers in one of them. The kind of shooting that I do though doesn't lend itself to a quick clean between volleys, anymore than brealking your 16 in half and trying to dislodge a stuck case with your cleaning rod in the middle of a firefight did. Clint won't wait. So, I work on getting the ring down with sweat equity. I haven't eliminated one yet but I have reduced them until there is no effect on velocity. I have yet to spin brass wool on the end of a drill - I am too faint-hearted for that, but I think I have tried every chemical and cleaning technique. It is a lot of work!You hit the nail on its head . Due to 150 rounds with no cleaning you have described the first step of improper cleaning. Maybe a little effort in at least using a pull through occasionally during the day might help. Remember....American ingenuity won the war.