I am breaking down some factory loads for my .257 Roberts because my gun will not stabilize 117 or 120 gr. Just going to pull the bullets and seat lighter ones with no other changes. I realize they may not be the most accurate but I don't want to trust the powder for anything else. The Hornady +P appears to have a Hornady 120 gr BTSP and ball powder. Anyone know what the powder is? Asking in case it groups well and I want to buy more.