I have an Argentine copy of a Browning HP. For a long time I've been annoyed by the loose frame to slide fit on the pistol. Heck it rattled from just holding it in my hand. I had read about peening slide rails, but was reluctant to, the whole beating on my gun with a hammer thing turned me off. I was looking at the gun yesterday and finally couldn't take it any longer. I've gotten pretty deep into hobby gunsmithing, so I said what the heck and give it a try. Read up on the process and off to the work bench I went. Peen then lap, peen then lap. When I was done, the frame to slide fit was much improved, no more rattle. Some of the painted on military grade finish got chipped off, but one day I'll strip it down and blue it.