SCRIDER1

I posted this in the guns forum and probably should have put it here first. Sorry, mods.

I recently came into posession of an old muzzleloader that is stamped Lymans Great Plains Rifle. Its a right-handed percussion model in 54 caliber. I know it is a reproduction, but I'm wondering if anyone can give me more details about it? How old it might be? What load I should try with it (I shoot 80 grains with my 50 cal. but I've never shot a 54). What kind of performance could I expect compared to a 50 cal, ect. Any info would be appreciated.

Thanks in advance!