I have the problem on 2 different pistols. One is a Dan Wesson Razorback and the other is a Rock Island Tac Ulta HC both in 10mm. After shooting several rds, and I haven't kept count the cartridges stop chambering. If I clean the chamber I'm back up and running. Not a huge hassle, but I don't have to do this with my 9's and 40's. Looking at my casts I can see a brown coating on the boolits. Perhaps I'm using too much lube.