I have in my collection some original 56/52 Rimfire ammunition for a Spencer. I believe the Spencer was made so well that you probably could shoot it but such would depreciate the weapon. Remember as time passes metal fatigue sets in. Metallurgy of the Civil War period was not what it is today. I have a reproduction Spencer Rifle made by Armi Sport, chambered in 56/50 Spencer, and it is a delight to shoot. I have to make my own ammo and it can get expensive but what the heck!