When I hunt with a .54 caliberroundball twist rifle, like 1-60 or slower, I load them 90-110 grains of Goex 2f powder, a moose milk patch and a roundball. With the slow twist in them, it seems you can really put the horse to them. The same even my 1-48 twist rifles. With 90 grains of powder under them, that ball is really moving. It has a lot of energy and all you need do is put that in the right place. If you want to plink, you can load them down to 50 grains of powder and they are usually accurate with that (which by the way would still kill a deer).

Something else to keep in mind is if you were to get a Great Plains Rifle with a 1-60 twist for shooting roundball, you can also purchase a Great Plains Hunter barrel only with a 1-32 twist for shooting large conicals like the 385, & 410 grain Great Plains Conicals if you really want to shoot some long distance and still inflict a world of hurt on something. The barrel are not all that expensive and they just switch out...

Mount a Lyman 57 SME(T)peep sight on them and you might surprise yourself at the degree of accuracy you will get. I have a Renegade with a T/C Huntingpeep sight and I once shot a 2" three shot group at 100 yards with it. For me and my eyes, that is real good. Normally I hold 4" and under.