Not that I have any idea what I'm doing, but I've tried the little Eze-Lap diamond files with my flint-eating Pedersoli pistol. It seems to work quite well, but how do I know since I don't know what I'm doing with these guns in the first place!
However, I do want to suggest that you might want to cover your lock with a rag when you do it. It seems likely that the process creates some very abrasive dust.