Some bases are pointed down deliberately - I think rarely would you have one pointed up (all with respect to line of bore). Picatinny rails can be had with varying minutes of offset for many bolt action and black rifles (well, really I don't care what color they are ). It would be nice if there was such flexibility in buying bases for muzzleloaders. A common problem nowadays involves scopes running out of upward adjustment before 100 yard zero is reached with the bp gun. Leupolds tend to have limited adjustment ranges compared to several other brands and are often involved when such problems arise. Be nice if a guy could just determine what offset is needed to get a scope to its optical center, then order accordingly. Shimming sux.

But that would be far too much to ask of the gun industry. Nowadays one is lucky to get a rifle with iron sights that actually work well on the rifle.