FFL question on a model 1863 falling block rifle
I have recently been thinking about rolling my own paper cartridges and seeing if I can find a falling block reproduction of a Sharps model 1863 target rifle. My question concerns the law for this type of firearm. It is a breech loader but only for black powder. I understand one can load it with loose powder or form a paper cartridge for the black powder load. I am most interested in forming the paper cartridge that is made up of boolit/black powder/thin paper to hold it together. It would then take a cap for the spark to set it off. I am seeking a knowledgeable opinion on this and I'm not trying to circumvent the FFL route. I haven't inquired anywhere else on this and thought I'd ask the great minds here first. Thanks for your opinion.