My original 1873 Trapdoor, mfg. in 1878, shoots Penn Bullets 500gr RNPB on top of 70gr compressed 2F about 3" high at 100yards. At least it groups about 4 MOA, given my inexperience with rifles I consider that pretty good. Too bad is also shoot 6" to the right!
I haven't tried to group the 405gr FPPB yet, I expect they would impact a little higher as the velocity would increase.
These are fun guns to shoot with Black Powder and will get attention at the range.