I agree that it will probably damage your nise old gun. I have been shooting steel no larger than #1 through one of my 97's but then again before I did I opened the choke up from full to modified. Has been no damage so far but again I am pushing 73 and have health problems so I won't be freezing my ass of in any duck blinds despite my love of waterfowling. Maybe a goose or two in a nice heated pit blind. Good luck and please don't ruin your great of H.D. Model 12. Chopperlump