I own the same rifle. I still shoot the 425 grain Hornady great plains bullets, but these will be the ones I will use, when I run out. As I understand, an under bullet felt is required, for the best accuracy. The reviews I've read, rave on them, and say they are very deadly on big game.
Andy3
https://www.muzzleloading-bullets.com/product/54-caliber-535-grains/
