.280 Ackley Improved
| .280 Ackley Improved | |
|---|---|
.280 Ackley Improved on the right, with .280 Remington | |
| Type | Rifle |
| Place of origin | United States |
| Production history | |
| Designer | P.O. Ackley |
| Manufacturer | Nosler |
| Specifications | |
| Parent case | .280 Remington |
| Case type | Rimmed, bottleneck |
| Bullet diameter | .284 in (7.2 mm) |
| Neck diameter | .315 in (8.0 mm) |
| Shoulder diameter | .454 in (11.5 mm) |
| Base diameter | .471 in (12.0 mm) |
| Rim diameter | .473 in (12.0 mm) |
| Case length | 2.525 in (64.1 mm) |
| Overall length | 3.330 in (84.6 mm) |
| Rifling twist | 1-9 |
| Primer type | large rifle |
| Maximum pressure (SAAMI) | 65,000 psi (448 MPa) |
The .280 Ackley Improved (.280 AI) was the result of the .280 Remington case modification by P.O Ackley, who pushed out the sidewalls at the shoulder to near parallel and steepened the shoulder angle to 40 degrees in order to increase powder capacity, thus along with increasing the allowable pressure, resulted in increasing the bullet initial velocity by approximately 100 fps.