Spencer Video

[Coal Creek Griff]

[Trailrider]

M1860 Spencer Carbine fired a .54 caliber bullet. The designation of ".56-56" came from the outside diameter of the cartridge case at the base and at the mouth of the cartridge case. Coincidentally, the cartridge was designated as a "#56".  In spite of the rear sight ladder being calibrated for 800 yds., effective range of 150 maximum was more like it. 
With the muzzleloading rifle musket being the standard infantry arm, the Spencer carbines and rifles, and the M1860 Henry Repeating Rifles were really Civil War assault arms!