I have an increasingly irrational, or perhaps irrationally increasing, desire to make a short-barreled, in-line muzzle loader rifle. Why? Because it would be fun.
So far I have determined that building one off a T/C Contender, T/C Encore, H&R 1871, Rossi S50, and a few other frames/actions would be a Very Bad Idea in the eyes of the government (at least, as I understand it, and it is probably always better to err on the side of caution when it comes to the authoritarian halfwits at the BATFE), that the muzzle velocity will, of course, suffer, and that the smokescreen from setting it off would be somewhere on the order of "epic". Is there anything else I should consider / be aware of, given my knowledge of black powder is… limited.
Anything other than "this is plain bonkers", that is.
Oh, and the serious reason behind doing this? Muzzle loaders, aside from the specific models mentioned above, are not considered "firearms" by the BATFE, and, as such, are not regulated in any fashion – you can, literally, purchase them online and have them delivered straight to your door. Likewise, they are not, so far as I can tell, regulated by the National Firearms Act, which means slapping a short barrel on one – arguably useless though it may be on a black powder rifle – requires no exorbitant tax stamp. Plus, with the general cost and unavailability of ammunition these days, BP might be a cheap way to get some actual trigger time.
Or, at least, it would have been until it started looking like the Boston bombings might have used black powder / gun powder, which means we can look forward to all kinds of interesting restrictions on either/both in the near future. So much for that plan.