The original Spencer cartridge — the first repeating rifle cartridge adopted by the US military. Fed 7 rounds through a tube in the buttstock of the Spencer repeating rifle, giving Union cavalry an overwhelming firepower advantage during the Civil War.
Type: Rifle
Introduced: 1860, United States
Parent case: None
Standardization: Obsolete / Non-standard
Bullet diameter: 0.55" (13.97 mm)
Case length: 0.875" (22.23 mm)
Overall length: 1.45" (36.83 mm)
Max pressure: 14,000 PSI
Rim type: Rimfire
Primer: Rimfire
Typical twist rate: 1:36
Muzzle velocity: 1000–1200 fps
Muzzle energy: 778–1150 ft-lbs
Effective range: 300 yd
Common bullet weights: 350, 360 gr
Primary use: Military, Hunting
Production status: Obsolete
Also known as: 56-56 Spencer · .56 Spencer · Spencer Rimfire
History: Christopher Spencer patented his repeating rifle and cartridge in 1860. The .56-56 was the original chambering: a straight-walled rimfire case with a 350–360 grain bullet. The Union Army purchased over 200,000 Spencer carbines and rifles during the Civil War — the largest military adoption of a repeating arm in history to that point. President Lincoln personally test-fired a Spencer rifle on the…
Notable firearms: Spencer Model 1860 Rifle, Spencer Model 1865 Carbine, Spencer Model 1867
Military use: {"country":"United States","years":"1863-1869","notes":"Union Army — cavalry, infantry; over 200,000 Spencer carbines and rifles purchased"}
Similar cartridges: .56-50 Spencer, .44 Henry