My P99 had a odd problem. where the backstrap met the frame, there was a edge , so to speak. as if the frame was to large for the backstrap. I tried all 3 encluded backstraps and even ordered another medium one from Earls. all the same. So i took an emory board (fingernail file) and LIGHTLY rounded the edge of the frame to meet the backstrap. after i was done i took a small peice of scrap leather, and useing the rough side of the leather, polished the frame smooth. now its comfy to hold!!