Do they weight 200gn? Are they 0.452" or larger diameter?
A hollowbase like that means you have to keep the velocity down. You go much about 850fps, and you will often get a 9-10 hole group from 5 shots or you'll stick a skirt and ring the barrel with your next shot.
Start low and stay low. You are aiming for very accurate loads at the 700-775fps range, so use a fast powder.