Have you tried the Buffalo Ballets?
My son's CVA Frontier Carbine .50 Hawkens shoots NICE groups at 100, with anywhere from 85 to 95 grains FFFg Goex...and they are only 245 gr, so recoil was a lot easier to handle for him when he was 12 when we built it, and I was so happy with the accuracy it is all we shoot in it.
He got his buck with it when he was 13, used 85 grains, shot it moving pretty fast quartering away from his stand from about 40 yds, it jumped a fence and ran about 30 feet farther and died...traveled a total of about 50 feet. From the upper back of the rib cage, it went through diagonally and down and exited the far shoulder. caught both lungs, and went completely through a rib and the shoulder, I was pretty happy with the penetration.
They look like two balls back to back, combined into one projectile, with the bottom one hollow, so you don't patch it, it loads and fires like a minie ball.
(I steal it when he's not looking and it's raining out too much for my flintlock.....