Rimfire · Proprietary · Not SAAMI standardized · Not standardizedObsolete
.56-46 Spencer
Necked-down Spencer family rimfire cartridge developed for improved velocity in post-Civil War Spencer sporting and military conversion rifles..
- Caliber
- 0.465″ · 11.81 mm
- Introduced
- 1866
- Case
- Rimmed
- Primary use
- Target, Small game
- Status
- Discontinued
- Obsolete
- Obsolete
- Introduced
- 1866
- Type
- Rimfire
- Origin
- United States
- Inventor
- Christopher Spencer
- Manufacturer
- Spencer
- Standard
- Proprietary · Not SAAMI standardized · Not standardized
- SAAMI
- Not SAAMI standardized
- Obsolete
- Obsolete
- Status
- Discontinued
- Availability
- Rare
- Case capacity
- 33.9 gr H₂O
- Twist (typical)
- 1:20
- Primer
- Rimfire
- Case type
- Rimmed
- Max pressure
- 14,000 CUP, SAAMI crusher
- Eff. range
- 200 yd
- Max range
- 3200 yd
- Recoil
- 14.4–14.7 ft·lb
Ballistics
Velocity only, no drag model: no published ballistic coefficient is on file for .56-46 Spencer, so this is the shape gravity alone gives the advertised velocity. Drag would steepen it. The tool below solves real loads through their published G1 or G7 model.
Open in Ballistic Compare- Parent case
- —
Representative trajectory — modeled from a single velocity input (no published BC for this cartridge yet).
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
SAAMI · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 11.81 | 0.465 | ~ |
| Neck ⌀ | 12.32 | 0.485 | ~ |
| Shoulder ⌀ | 14.20 | 0.559 | |
| Shoulder angle | 15° | — | |
| Base ⌀ | 14.22 | 0.560 | ~ |
| Rim ⌀ | 16.38 | 0.645 | ~ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.92 | 0.076 | |
| Neck length | 12.19 | 0.480 | |
| Case length | 26.42 | 1.040 | ~ |
| Overall length | 33.61 | 1.323 | |
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. .56-46 Spencer is highlighted below.
Missing a dimension for .56-46 Spencer? Some case measurements aren't in a published SAAMI/CIP drawing yet. Have a factory or reamer print? Send it → — verified hard-to-find data earns a free Lindcott sticker.
Firearms chambered in .56-46 Spencer
Connected reference
History
The .56-46 Spencer was developed after the Civil War as an improved loading for the Spencer repeating rifle, using a necked case to achieve higher velocity than the straight-walled .56-56 Spencer. It was used in later Spencer production and conversion rifles through the late 1860s before lever-action centerfire arms supplanted rimfire Spencers.
FAQs
- What twist rate does .56-46 Spencer use?
- .56-46 Spencer typically uses a 1:20 twist rate.
- What bullet diameter is .56-46 Spencer?
- .56-46 Spencer uses a 0.465″ (11.81 mm) diameter bullet.
- Is .56-46 Spencer still in production?
- .56-46 Spencer is discontinued; typical availability is rare.
- What is .56-46 Spencer used for?
- .56-46 Spencer is primarily used for target, small game.
Sources & provenance
- Reference Gun Digest Books — Cartridges of the World (Frank C. Barnes) — obsolete rimfire section, .56-46 Spencer entry · grain weights, year, bullet ⌀, velocity
- Secondary Wikipedia — .56-56 Spencer (covers the .56-46 necked variant) · grain weights, bullet ⌀ archived
Data & sources. Specs compiled from the Lindcott Armory reference; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
