I have a .455 rechambered to 45 colt,,It shoots shotgun patterns with .451 bullets...Check your cylinder mouths by dropping a .451 bullet into them,,They fall right through my cylinder..I got a .456 220 grain bullet mold and shrunk the groups down to around 4-5 inches at 25 yards,,Nothing to brag about ,,but waaaay better than the .451 bullets.