Hi, I have no experience with actual muskets but I do load 45-70 with black powder and the substitutes to shoot out of my trapdoors and I also load 8x56R Kropatschek using black powder and its substitutes. I have loaded Pyrodex and Triple 7 in both cartridges with acceptable results. I am not really shooting for groups most of the time as I usually just enjoy shooting steel at about 120 yards. In my 1888 Trapdoor and 1879 trapdoor carbine do fairly well. it is easy to compress the powder in the case. In the bottle necked 8x56R Kropatschek it is a little more difficult but I have been able to get fairly consistent hits at 120 yards. I guess the moral of the story is that the substitutes do fine with the added bonus of not smelling like someone went to the bathroom in their pants next you. Sorry I didnt reply sooner. Just seen this. Hope this helps a little bit.