I have a Stainless 4.2" GP100 and have fired thousands of hand loads using Alliant Bullseye powder. My revolver is about 8 years old and has no signs of wear or erosion such as yours, the edge is still nice and sharp. As others have stated this is not normal. As for Snap Shots I have heard they are rather busy but I had a great experience with them. I had a 10/22 with a cracked receiver, I contacted them by phone and sent them pictures. They had me send the rifle to them and in a couple weeks I received the rifle back with a new receiver with no fees other than the shipping to them. They took care of me.