hey, should have just asked me ive got one and so does a buddy of mine we both have the Buckhunter Pro .50 cal. In-Line Pistol , we figured out a patched roundball with 50 to 60 grains pyrodex shoots great but you have already figured that out, also a 245 grain power belt with no less then 60 grains under it works good. pretty much anything 300 grains and under works the best, If i remember correctly its been along time since i shot it it has a 80 grain charge capacity but most loads worked the best with 60 to 70 grains. hope that helps