in that cartridge.
After various tries, found a gentleman at Black Hole Weaponry who thought it a very interesting idea and was willing to do the barrel work, and brought up a couple of questions, one of which is what's ended this. Question was on working the rimmed case with a AR-10 bolt & barrel. I've been using some ideas for this and the magazine from looking at a PSL; rimmed cartridge in a semi-auto rifle. So I finally had a chance to look at it again, and field-strip it to get pictures of the breech
Ah well. Now I have a perfectly good AR-10 upper I need to do something with. This requires thought.