I have used some formulas that say a 300gr+ slug wont shoot well, but I have shot some that heavy made by Buffalo Bullet co, and they shot great, cloverleafs at 50 yds. Not a big fan of the lee Real bullet for several reasons I wont bother you with. If you know of a mold, that casts a slug as described, and have first hand knowledge of shooting same in a TC.45, 1-48 twist, please let me know. I am also thinking of ordering a proud .44 slug mold, and paper patching it.