He is carrying a rare M1855 rifle (shorter than its relative the M1855 rifle/musket) with sword bayonet. The blade is 21 3/4 inches long. A standard socket triangular blade bayonet was 18-19 inches long. So, yeah, it was long. That extra length didn't help them any at 1st Manassas against J.E.B. Stuart's Cavalry.

David