The sights on the P'53 rifle-musket and P'56 Enfield rifles are graded out to 900 yards. And, for that matter, the M1855 and M1861 Springfield rifle-musket are set up for out to 500 yards.

Apparently they used them... since both Hardee's and Casey's tactics manuals contain instructions for firing at long range while in skirmish order, using the ladder sights. It looks like you're shooting at airplanes, but we've been able to land a few rounds close at that range ;-)

Tom