I have a MGM barrel on my contender in 22 Hornet. Sometimes the hammer falls but the gun does not fire and there is no indentation in the primer. I have noticed that any time that I don't close it up quite sharply that this happens. I can open it back up and close it with a little extra snap and it will then fire. Serial # 2001XX and has the safety on the hammer. Any suggestions and ideas will be appreciated. Thanks. Jim