probally from leaving oil in the bore...i shot my first shot at game and never have a problem...i run a bunch of dry patches through to make sure its dry though...my dad actually told me to quit last year before the first day of deer season because i did it 3 times the night before because i wasnt sure if i did it and how good it was done lol..thats probally your problem..it shouldnt be bad off maybe a few inches at the most....