Popped a sitting cottontail with a prb from my .50 cal flintlock Saturday. Was still hunting for deer, but I'd never pass up a fried rabbit supper. 80 grains Goex is surely overkill, but that's what was in the tube, so... Didn't turn out too bad as it hit right at the head/neck junction. Just one less thing I had to cut off & discard when I dressed it.
Would love to have a smoothbore flinter, but don't think there is a drop-in shotgun barrel on the market for my gun, and a new gun is out of the question for now. But it's first on my list when funds are available!