Caliber Description
The .308 Winchester Ackley Improved (AI) is a stretched and modernized variant of the classic .308 Winchester cartridge, a benchrest and hunting staple since its introduction in 1952. The wildcat cartridge's origin lies with P.O. Ackley, an influential gunsmith and cartridge designer, who developed the "Improved" versions by steepening the shoulder angle and straightening the case wall of factory brass. This allowed more powder capacity, less case stretching, and often improved accuracy, velocity, and efficiency. Wildcatting the .308 Win remained relatively underground until the reloading and shooting communities saw the potential in increased velocity without the need for a larger magnum receiver, blending the best of efficiency and performance.
Today, the .308 Win. Ackley Improved sits in a sweet spot for reloaders, long-range shooters, and hunters who want more from their standard .308 rifles. By fire-forming standard .308 brass in a chamber cut for the Ackley Improved dimensions, reloaders unlock approximately 5-8% more case capacity. This increases muzzle velocities by 100 to 150 fps over the parent cartridge with similar pressure, ideal for maximizing flat trajectories in precision target shooting. The AI version maintains excellent case life, and factory .308 Winchester ammunition can still be fired safely, making it a versatile platform for reloaders who already own a .308 Win rifle and want to upgrade their performance without purchasing an entirely new setup.
A popular application for the .308 Win. Ackley Improved is both in competitive target shooting and big game hunting. For shooters competing in F-Class, tactical matches, or high-power rifle events, it provides the desirable balance between recoil, barrel life, and downrange ballistics. Hunters, especially in North America, find the extra velocity yields better terminal performance and a flatter trajectory for longer-range shots on medium- to large-sized game. The increased powder capacity doesn't add significant recoil, making it comfortable and effective for field use, including elk, deer, antelope, and even black bear. It’s also a practical choice for those who want to maximize their .308 Winchester rifles for long-range varmint or predator hunting.
Reloaders will appreciate the range of bullet weights and styles that work well in the .308 Win. Ackley Improved. Typical bullet weights range from 150 grains up to 180 grains for hunting, with match shooters trending towards heavier bullets in the 178- to 185-grain range for superior ballistic coefficients and wind-bucking capability. The AI chamber's steeper 40-degree shoulder enhances case longevity by reducing brass flow and case stretching, making it both efficient and cost-effective for those loading in high volumes. With its standard short-action compatibility and a wealth of readily available .308 Win. brass, dies, and projectiles, the .308 Win. Ackley Improved is a flexible, potent option for reloaders aiming for top-tier precision and performance from a classic cartridge lineage.
Popular Load Recipes
- 150 gr Nosler Ballistic Tip, 49.0 gr IMR-4064, CCI 200, OAL 2.800", velocity ~2960 fps
- 155 gr Hornady A-Max, 50.0 gr Varget, Federal 210M, OAL 2.820", velocity ~2950 fps
- 168 gr Sierra MatchKing, 47.5 gr RL-15, CCI BR2, OAL 2.830", velocity ~2800 fps
- 175 gr Sierra MatchKing, 46.0 gr Varget, CCI 200, OAL 2.830", velocity ~2740 fps
- 178 gr Hornady ELD-X, 46.5 gr H4895, Federal 210, OAL 2.820", velocity ~2760 fps
- 180 gr Nosler Partition, 47.0 gr IMR-4350, Winchester WLR, OAL 2.800", velocity ~2750 fps
- 190 gr Berger VLD, 45.0 gr RL-17, CCI 200, OAL 2.950", velocity ~2700 fps
- 200 gr Sierra MatchKing, 44.0 gr H4350, Federal 215, OAL 2.900", velocity ~2600 fps
Always verify loads with a trusted manual and start lower, working up while watching for overpressure signs. These Ackley Improved loads are approximations based on commonly reported data—exact safe maximums depend on your rifle and brass.
Cost per Reloaded Round
To calculate savings per round by reloading .308 Win. Ackley Improved compared to buying factory ammo, let's use approximate 2024 prices in the US:
Factory .308 Win. Ackley Improved ammo is rare, but custom/limited factory loads can cost about $2.50–$3.00 per round. We'll use $2.75 as an average.
Reloading component costs per round (approximate):
- Brass: $1.00 each new, but reloaded 10 times = $0.10 per load
- Primer: $0.08
- Powder: 45 grains (approx 0.065 lb per round), 1 lb = $40 (7000 gr/lb), $40/7000*45 = ~$0.26
- Bullet: $0.40 (match, eg. Sierra, Hornady, etc.)
Total reload cost: $0.10 (brass) + $0.08 (primer) + $0.26 (powder) + $0.40 (bullet) = $0.84 per round
Savings per round: $2.75 (factory) - $0.84 (reload) = $1.91 per round
You save about $1.91 each time you reload instead of buying factory .308 Win. Ackley Improved ammunition.
Technical Specifications
Safety Standard / Application
C.I.P. / Rifle Caliber
Most Suitable Bullet Weights
112 - 208 Grains
Case Capacity / Average Charge
59 Grains of Water / 43.7 Grains
Average Muzzle Velocity / Energy
2667 fps / 2455 ft-lbf
Case Length / Max. C.O.L
2.014'' / 2.8''