I was recently given a knight 50 cal disc muzzle loader. The gun is approximately 15 years old I can't find what model it is. I am in process of trying to clean it up. On all tutorials it says on upper left hand side is a pin you pull out to release bolt. This one has a allen screw. I unscrewed this but still unable to pull bolt out. What am i doing wrong? I am a very dumb newby!!!!!!