we all have t/c hawkins .50 cal. AL of them shoot the MAXI-BALL not those MAXI-HUNTER real good. i use .370 gr maxi-ball. thompson told me they get on test rifles ,3/4 inch group with the MAXI-BALL. i can touch holes at 50 yards with 80 grs.of 2f with a wonderwad and bore butter and a 370 MAXI-BALL. they should shoot well out of your gun, if not, send it in to THOMPSON.