Cartridge comparison
.256 Gibbs Magnum vs .257 Ackley Improved
.256 Gibbs Magnum and .257 Ackley Improved are both in the reference; see the full spec comparison below.
Side by side
| .256 Gibbs Magnum | .257 Ackley Improved | |
|---|---|---|
| Type | Rifle | Rifle |
| Introduced | 1913 | 1945 |
| Bullet diameter | 0.265″ | 0.257″ |
| Case length | 2.1752″ | 2.3331″ |
| Max pressure | 49,313 psi | 54,000 psi |
| Recoil | 11.6 ft·lb | 9–13 ft·lb |
| Effective range | 300 yd | 400 yd |
| SAAMI | Not SAAMI standardized | Wildcat |
| CIP | CIP standardized | Not standardized |
| Obsolete | Obsolete | — |
Highlighted cells hold the clear edge where both sides have a number. Every figure is a range maximum from the reference; typical loads run lower.
Case profiles, to scale
Drawn to the same scale, so the proportions are true. Physical size varies with your screen.
