Grouse thanks for taking the time to do the testing. I did get out last Wednesday with 3 generations of .45's, The SS .45 DISC I got from you, a NIB .45 ELITE, and my old go to ORIGANAL .45 1-20, all 3 had the LEIGH CONVERSIONS. The Disc & Elite were spottless in the plug & bolt area. The 1-20 was another story, lots of blow by in the plug & bolt area. The HEAD Space must be differnt, I know this is something Leigh & Knight will be able to work out. I was shooting 70 grs. by weight of BH-209, blue harvester sabots & 40x200 XTP's at 50 yds, they were printing almost 1 hole groups. THANKS.