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.

History

In 1957 Remington introduced the .280 Remington, which was based on the

.30-06 Springfield The .30-06 Springfield cartridge (pronounced "thirty- aught-six" ), 7.62×63mm in metric notation, and called the .30 Gov't '06 by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in military us ...

case necked down to 7mm. The cartridge was intended to compete with the .30-06 and the .270 Winchester. Although the .280 Remington is considered to be a very balanced cartridge combining the best attributes of both cartridges due to the high ballistic coefficient and sectional density characteristic of 7mm calibers, it did not reach the popularity achieved by the .30-06 and .270 Win. The famous wildcatter P.O Ackley worked on the .280 Remington case in order to add it to the line of "Ackley Improved" cartridges and named it the .280 Ackley Improved 40 degrees. By 2008, Nosler standardized it and SAAMI accepted it. Ever since, the .280 Ackley Improved has earned great popularity in the US market. Several different companies manufacture rifles chambered in .280 AI, including the Ruger M77 Hawkeye, Savage 110,

Browning X-Bolt The X-Bolt Rifle is a bolt-action rifle designed by the American Browning Arms Company. It is manufactured by Miroku Corp. in Japan. Description The X-BOLT rifle is a bolt-action rifle. Its name comes from the "X-Lock" scope mounting system. I ...

and

Weatherby Mark V The Weatherby Mark V is a centerfire, bolt-action rifle manufactured by Weatherby of Sheridan, Wyoming. The rifle was introduced in 1957 by Weatherby and was designed to safely contain the high pressures associated with the Weatherby line of high ...

Design

The .280 AI is basically the .280 Remington redesigned by steepening its case shoulder and straightening the sidewalls to near parallel, thus resulting in an increased powder capacity giving 100 fps greater muzzle velocity, comparable to the

7mm Remington Magnum The 7mm Remington Magnum rifle cartridge was introduced as a commercially available round in 1962, along with the new Remington Model 700 bolt-action rifle. It is a member of the belted magnum family that is directly derived from the venerable . ...

. A .280 Remington cartridge fired from a rifle chambered in .280 Ackley Improved will result in a case formed for the latter, which may be used for reloading.

Performance

280 Ackley Improved Vs. 280 Remington

Loaded with a 150 grain bullet, the .280 AI shot from a 24" barrel gives a muzzle velocity of approximately 3,060 fps, which is about 100 fps faster than a .280 Remington loaded with a bullet of similar weight. Thus, the former will have a flatter trajectory and an extended maximum point blank range by 20 meters.

280 Ackley Improved Vs. 270 Winchester

A 150 grain bullet shot from a .280 AI generates a muzzle velocity similar to the .270 Winchester firing a 130 grain bullet. Being a heavier projectile, the .280 AI carries 15% more energy than the 130 grain bullet, and with flatter trajectory & further maximum point blank range. If both cartridges are fired with bullets of the same weight, the .280 AI bullet travels faster with a flatter trajectory but the .270 Win offers 5% higher sectional density.

280 Ackley Improved Vs. 7mm Remington Magnum

According to Nosler reloading data, although the 7mm Remington Magnum does not provide more than 50 fps over the .280 AI with similar projectiles, the latter cartridge holds less powder in its case, thus it is considered more efficient. However, the published data is provided from a .280 AI tested with a 26" barrel rifle, while the 7mm Rem Mag was tested with a 24" barrel, which suggests that the velocity advantage should increase in favor of the 7mm Remington Magnum if both cartridges were tested from rifles with similar barrel lengths, and especially from reloads. An advantage to the 280 AI vs 7mm RM is an additional round capacity in typical internal rifle magazines with a minor penalty in performance and reduced recoil.

Sporting use

For practical purposes, the .280 Ackley Improved is similar to the .270 Winchester, 30-06 Springfield and .280 Remingon. In other words, energy and maximum point blank range for this line of cartridges is similar, making them suitable for mid size big game such as

white tail deer The white-tailed deer (''Odocoileus virginianus''), also known Common name, commonly as the whitetail and the Virginia deer, is a medium-sized species of deer native to North America, North, Central America, Central and South America. It is the ...

and Dall ram. With the correct bullets, any of these cartridges is suitable for larger game such as

elk The elk (: ''elk'' or ''elks''; ''Cervus canadensis'') or wapiti, is the second largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. ...

and red stag.

References

{{.30-03 Springfield Pistol and rifle cartridges