The standard M-55 socket Springfield bayonet used by US forces should fit your Richmond. Many of these bayonets were used and undoubtly ended up on the end of a Richmond musket. It really didn't matter to CS soldiers what type bayonet they had, as long as it fit. Enfield and Springfield bayonets were interchanged at times. Several vendors made bayonets for the Richmond Depot. Perhaps the best known (and the only one I know of) are the socket bayonets without a fluted blade made by the Raleigh bayonet factory. If you want to get one of these for your Richmond, the prices start at about 700 or 800 dollars for one in rough condition (if you can find one for sale). My advice is take your Richmond to an antique gun show and find a US model that fits.