Rifle · Not SAAMI standardized · Not standardizedObsolete
.56-56 Spencer
The original Spencer cartridge — the first repeating rifle cartridge adopted by the US military.
- Caliber
- 0.55″ · 13.97 mm
- Introduced
- 1860
- Case
- Rimfire
- Primary use
- Military, Hunting
- Status
- Obsolete
- Obsolete
- Obsolete
- Introduced
- 1860
- Type
- Rifle
- Origin
- United States
- Inventor
- Christopher Miner Spencer
- Manufacturer
- Spencer Repeating Rifle Company
- Standard
- Not SAAMI standardized · Not standardized
- SAAMI
- Not SAAMI standardized
- Obsolete
- Obsolete
- Status
- Obsolete
- Availability
- Collector Only
- Case capacity
- 32.2 gr H₂O
- Twist (typical)
- 1:36
- Primer
- Rimfire
- Case type
- Rimfire
- Max pressure
- 11,600 CUP, SAAMI crusher
- Eff. range
- 300 yd
- Max range
- 2700 yd
- Recoil
- 10–16 ft·lb
- Subsonic
- Capable
Ballistics
Published velocity/energy data isn't available for .56-56 Spencer — an obsolete/collector cartridge.
Performance
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
Wikipedia · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 13.97 | 0.550 | ~ |
| Neck ⌀ | 14.22 | 0.560 | · |
| Shoulder ⌀ | n/a | ||
| Shoulder angle | n/a | ||
| Base ⌀ | 14.22 | 0.560 | · |
| Rim ⌀ | 16.38 | 0.645 | · |
| Belt ⌀ | n/a | ||
| Rim thickness | 2.53 | 0.100 | |
| Neck length | n/a | ||
| Case length | 22.23 | 0.875 | · |
| Overall length | 39.24 | 1.545 | · |
Size vs familiar rounds
Drawn at true 1:1 — every case is accurate relative to the others. Absolute size depends on your screen's pixel density, so measuring one against a real ruler may be off. .56-56 Spencer is highlighted below.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Firearms chambered in .56-56 Spencer
Lineage
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 White House lawn in 1863 before authorizing mass procurement. The 7-round tube magazine fed through the buttstock; a skilled trooper could fire 14–20 rounds per minute using pre-loaded tubes from a Blakeslee cartridge box. Confederate forces were so outgunned at the Battle of Hoover's Gap (1863) that they reportedly believed they faced an entire division. The .56-56 was superseded by the slightly more powerful .56-50 Spencer as the war progressed. Both became obsolete with the adoption of centerfire cartridges in the late 1860s.
FAQs
- What twist rate does .56-56 Spencer use?
- .56-56 Spencer typically uses a 1:36 twist rate.
- What bullet diameter is .56-56 Spencer?
- .56-56 Spencer uses a 0.55″ (13.97 mm) diameter bullet.
- Is .56-56 Spencer still in production?
- .56-56 Spencer is obsolete; typical availability is collector only.
- What is .56-56 Spencer used for?
- .56-56 Spencer is primarily used for military, hunting.
Sources & provenance
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 1 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
