The Colt M1855 Repeating Rifle aka (Colt-Root) is a strange beast because Colt seemed to have been unable to make up their minds on caliber (>40- .64 with .44, .50. and .56 being the most common. AND, barrel lengths in 24, 27, 31 5/16, and 37 1/2 inches.
The artillery carbine took a German Solingen made sabre bayonet had a straight 24 1/8 inch long blade. if anyone has ev er handled a saber bayoneted rifle, they are hideously awkward and clumsy to use and a curse for bayonet drill.
Just under 5500 were delivered to the government. While Berdan's Sharpshooters were waiting on Sharps to make their special NM1859 Sharps Rifles in 1862, they got M1855 Colt Rifles.
They were rather unpopular. If using non Colt factory ammo... and as they were used and worn... undersized cartridges and or ill fitting percussion caps saw numerous chain-fires. One Berdan wrote that after a target practice, one had chain-fired and they the man had to have the surgeon pick and dig lead splinters out of his forearm.
I almost bought one of the Italian repro's, but when released they were only the more 'civilian' .44. Almost immediately, teh chain fire thing popped up and Dixie Gun Works slashed the price then pulled them from sales. Later, when the fervor had run its course and died down, they re-released them.
The Italians did offer a .58 (close enough I guess for Italian work...) but by that time I was no longer "doing" a Berdan impression.