[Why on God's Green Earth would you even consider taking a chance with a valuable piece of American history?

A: there is no "chances" taken. no harm will or can be done.

Oh and there is no way on God's Green Earth that the barrel on my original Trapdoor is as hard as the one on my replica,

A: who cares.

mainly because they didn't have the technology bad then to make then hard enough for jacketed bullets, which didn't exist to start with

A: so what. The STEEL in those barrels is more than "hard enough" for jacketed bullets. You can "believe" whatever you like, but this won't change reality.

Frankly, I can cast a "plethora" of various lead bullets that are just as accurate as commercial jacketed bullets, but at 25-30 bucks per 50 in a box, it's pretty silly to buy em these days! LOL