The Mk IV Is Running!

I think the problems with my Mk IV are solved. When I first got it, it would stovepipe about every third round. I spotted a rough place that was grabbing lead and brass in the chamber, polished that out with valve grinding compound, and then it would stovepipe once or twice per magazine. 

I looked it over again and spotted another problem. The boss on the front end of the guide rod assembly is a stamped steel piece, and it was rough. A spot on it was making a drag mark at the top of the receiver tube, straight back from the bore. I took the spot off with a fine file, then worked it with a diamond hone, and finished with a 1200 grit diamond hone. I took it to Pistol League this week and ran two turns with it (50 plates) and it ran like a champ with no malfunctions.