My experience with muzzle loading rifles is comparable. One thing I found interesting was the acurracy of loose unpatched balls in a rifle. Groups tended to run 4" to 6" at 50 yards. Still acurrate enough to be militarily effective. My experience as a full time range officer was that most misses with both rifles and shotguns tend to be high with untrained shooters. Training seems to be the key. My undocumented theory is that the British rifles were more effective at least for the first few shots and no worse than a musket after that.