Authored By Dan Alex (Updated: 9/23/2015):
Design of the Spencer Rifle included a wooden shoulder stock with integral straight grip, metal receiver, wooden forend and long-running section of exposed barrel with three barrel bands joining it to the forend. The hammer was external and offset to the right side of the body as in preceding flintlock and percussion-based designs. A flip-up type sighting device was ahead of the receiver with a simpler sighting device just aft of the muzzle. The trigger unit sat under the grip handle with the lever doubling as the trigger guard. Sling loops were located under the shoulder stock and at the second barrel band for use of an optional shoulder strap. Barrel lengths were variable depending on the Spencer model in question, ranging from 20- to 30-inches long.
The rifle was chambered for the unique .56-56 Spencer rimfire cartridge feeding from a 7-round internal tube magazine located in the buttstock. The magazine tube was spring-loaded at its rear, the cartridges aligned in single file order and fed into the firing chamber in turn. The magazine was locked into place within the butt by a rotating release/catch which had to be positioned 90-degrees of center for removal of the tube. The action relied upon manual management of the lever which introduced a fresh cartridge into the chamber and cleared any spent shell casings therein (ejecting downwards). The lever was brought down at a forward angle which worked the internal action against the magazine. When brought back up against the stock, the cartridge was firmly in place. The hammer was then manually cocked to bring the gun into a proper firing condition (for each successive shot as the hammer was not automatically actuated by management of the lever). In this arrangement, the operator could supply a repeat-fire pattern, reaching rates-of-fire of 14- to 20-rounds per minute - a great advantage concerning rifles of the day. Cartridges of the period still relied on black powder which gave off excessive amounts of smoke during the action. Reloading was either through manual means by dropping individual rounds into the buttstock opening (through the open rear by way of the removed magazine cover/tube) or by prefabricated cartridge boxes known as the "Blakeslee Cartridge Box", these available in variable counts.
Effective range of Spencer Rifles was listed at approximately 500 yards which gave it a substantial reach on the battlefield. Muzzle velocity was in the range of 1,000 feet per second which gave the bullet good penetration values at range as well.
The "Spencer Carbine" was nothing more than a shortened, lightened and more compact form of the base Spencer Rifle appearing after 1863. In this modification, both the forend and barrel were noticeably shortened to make the weapon more portable - extremely suitable for horse-mounted infantry and specialist troops requiring an easy-to-tote primary firearm.