wood stocks were an option on the black mountain magnum. i have seen some in that configuration while searching on the internet. they are harder to come by, though, and it MAY be that the wood stock was only offered on the ones in .54 caliber (not absolutely sure about that, though. i just know that there was a .54 caliber model that came with a wood stock).
it came standard with a musket nipple. basically, it was a new englander with a longer barrel (28" instead of 26". curiously, the synthetic-stocked version of the new englander had a 24" barrel). i believe the BM mag also had stronger hammer springs to keep the hammer from blowing back to half-cock with stronger powder charges (BM mag is rated to 150 g. powder charges, new englander only 100 g. [110 w/ roundball]). the BM mag also had fiber optic sights and was drilled/tapped for a scope mount (new englander was not). i have a T/C greyhawk, which is a stainless steel version of the new englander (24" barrel, 1-48" twist). it's a great rifle.
i am pretty sure that the .50 caliber black mountain magnum had a 1-28" twist barrel (compared to 1-48" for the new englander) and the .54 BM mag had either a 1-38" or 1-48" twist barrel. this is based on some old t/c catalogs i have