I have a chopped Replica 1863 Remington contract rifle. Good hunting accuracy with 80 grains of fffg, a 440 grain REAL, (which actually casts out at 456) and a wonder wad under the bullet. I have recently switched to a bee's wax wad under the wonder wad in my other .58" rifles, but have not tried it in this one.
I initially went to the wax-wad under the wonder wad to keep the wonder wad from contaminating the powder, but have found it makes a really good gas seal. Bonus! If you are not worried about powder contamination, (as in target shooting) I also found that two wonder wads work better than one.
Bang is right, the shallow groove rifling on these rifles does shoot round ball well. I have never had any luck with minie's as they require light powder charges.
On both my chopped and normal 1863 Remington contract rifles, I had to put a lower rear sight on them. On my 1861 I only had to file down the front sight, notch the little square block, and then solder in a taller blade. They will all shoot high without some modification to the sights.
My 1861 shoots both PRB and the REAL to the same POA.
