Rifle · Not SAAMI standardized · Not standardizedObsolete
.255 Rook
British "rook and rabbit" rifle cartridge for lightweight single-shot sporting rifles.
- Caliber
- 0.255″ · 6.477 mm
- Introduced
- 1880
- Case
- Rimmed
- Primary use
- hunting
- Status
- Obsolete
- Obsolete
- Obsolete
- Introduced
- 1880
- Type
- Rifle
- Origin
- United Kingdom
- Inventor
- Various British
- Manufacturer
- British gunsmiths / various
- Standard
- Not SAAMI standardized · Not standardized
- SAAMI
- Not SAAMI standardized
- Obsolete
- Obsolete
- Status
- Obsolete
- Availability
- Antique
- Case capacity
- 14.5 gr H₂O
- Twist (typical)
- 1:14
- Primer
- Large Rifle
- Case type
- Rimmed
- Max pressure
- 18,000 psi, CIP transducer
- Eff. range
- 100 yd
- Max range
- 2550 yd
- Recoil
- 0.5–0.51 ft·lb
- Subsonic
- Capable
Ballistics
Published velocity/energy data isn't available for .255 Rook — 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.
SAAMI · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 6.48 | 0.255 | ~ |
| Neck ⌀ | 6.96 | 0.274 | |
| Shoulder ⌀ | 7.12 | 0.280 | ~ |
| Shoulder angle | 15° | — | |
| Base ⌀ | 8.74 | 0.344 | ~ |
| Rim ⌀ | 10.19 | 0.401 | ~ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.20 | 0.047 | |
| Neck length | 6.69 | 0.263 | |
| Case length | 29.21 | 1.150 | ~ |
| Overall length | 36.32 | 1.430 | ~ |
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. .255 Rook is highlighted below.
Missing a dimension for .255 Rook? 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.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Reloading costestimate cost per round vs factory
Estimate your cost per round and how it compares to factory. Inputs are yours — nothing is stored.
Cost estimate only — not load data. Charge weight is your input; follow published manuals for safe charges.
History
A British rook rifle cartridge from the Victorian era, chambered in small single-shot sporting rifles used for vermin control. The "rook rifle" tradition was unique to Britain, with specialized small-caliber cartridges for pest control on estates. Completely obsolete by the early 20th century.
FAQs
- What twist rate does .255 Rook use?
- .255 Rook typically uses a 1:14 twist rate.
- What bullet diameter is .255 Rook?
- .255 Rook uses a 0.255″ (6.477 mm) diameter bullet.
- Is .255 Rook still in production?
- .255 Rook is obsolete; typical availability is antique.
- What is .255 Rook used for?
- .255 Rook is primarily used for hunting.
Sources & provenance
- Standard SAAMI — SAAMI cartridge & chamber drawing — .255 Rook archived
- Standard SAAMI — ANSI/SAAMI Z299 — Cartridge & Chamber Drawings archived
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 4 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
