Rifle · CIP · Not SAAMI standardized · CIP standardizedObsolete
.256 Gibbs Magnum
.256 Gibbs Magnum is a rimless bottlenecked rifle cartridge of United Kingdom origin.
- Caliber
- 0.265″ · 6.73 mm
- Introduced
- 1913
- Case
- Rimless
- Parent
- 6.5x57mm Mauser
- Primary use
- Hunting
- Status
- Obsolete
- Obsolete
- Obsolete
- Introduced
- 1913
- Type
- Rifle
- Origin
- United Kingdom
- Inventor
- George Gibbs of Bristol
- Manufacturer
- Gibbs
- Standard
- CIP · Not SAAMI standardized · CIP standardized
- SAAMI
- Not SAAMI standardized
- Obsolete
- Obsolete
- Status
- Obsolete
- Availability
- Collector
- Case capacity
- 57.8 gr H₂O
- Twist (typical)
- 1:8
- Primer
- Large Rifle
- Case type
- Rimless
- Max pressure
- 49,313 psi, CIP transducer
- Eff. range
- 300 yd
- Max range
- 1500 yd
- Recoil
- 11.6 ft·lb
Ballistics
Velocity only, no drag model: no published ballistic coefficient is on file for .256 Gibbs Magnum, 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
- 6.5x57mm Mauser
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.
CIP TDCC · verified| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 6.73 | 0.265 | ✓ |
| Neck ⌀ | 7.62 | 0.300 | ✓ |
| Shoulder ⌀ | 10.82 | 0.426 | ✓ |
| Shoulder angle | 20.1° | — | ≈ |
| Base ⌀ | 12.01 | 0.473 | ✓ |
| Rim ⌀ | 12.09 | 0.476 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.02 | 0.040 | ✓ |
| Neck length | 6.05 | 0.238 | ≈ |
| Case length | 55.25 | 2.175 | ✓ |
| Overall length | 77.47 | 3.050 | ✓ |
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. .256 Gibbs Magnum is highlighted below.
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.
Lineage
Connected reference
History
Introduced around 1913 by George Gibbs of Bristol, derived from the 6.5x57mm Mauser.
FAQs
- What twist rate does .256 Gibbs Magnum use?
- .256 Gibbs Magnum typically uses a 1:8 twist rate.
- What bullet diameter is .256 Gibbs Magnum?
- .256 Gibbs Magnum uses a 0.265″ (6.73 mm) diameter bullet.
- Is .256 Gibbs Magnum still in production?
- .256 Gibbs Magnum is obsolete; typical availability is collector.
- What is .256 Gibbs Magnum used for?
- .256 Gibbs Magnum is primarily used for hunting.
- What is .256 Gibbs Magnum based on?
- .256 Gibbs Magnum is derived from the 6.5x57mm Mauser case.
Sources & provenance
Data & sources. Specs compiled from the Lindcott Armory reference; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
