Many hunters will be surprised to learn that the .280 Ackley Improved (AI) is about as old as the .300 Winchester Mangum.

Winchester introduced the .300 Win. Mag. in 1963. Around the same time, gunsmith and wildcatter P.O. Ackley began tinkering with the .280 Remington, and his wildcat redesign retained enough of a following among hunters and shooters that Nosler introduced the .280 AI as a factory cartridge—but not until 2007.

Though they’re about the same age, the .300 Win. Mag. enjoys a much more substantial reputation. Prior to 2007, hunters were forced to build a custom rifle if they wanted to use Ackley’s design, and it’s still more difficult to get your hands on a .280 AI than a .300 Win. Mag. (More on that below.)

But they are still closely matched as hunting cartridges, and the .280’s star is rising. We wanted to know: If you’re looking for an all-around big game rifle, can the .280 AI eclipse its much more famous brother?

Ballistics There’s no question that, generally speaking, the .300 Win. Mag. packs a heavier punch than the .280. Bullets capable of travelling between 2,700 and 3,200 feet per second (fps) are available for both cartridges, but if you compare bullets of the same weight, the. 300 Win. Mag. flies faster.

Federal’s 155-grain .280 AI, for example, travels 2,930 fps at the muzzle, while their 150-grain .300 Win. Mag. load travels 3,150. That 200- to 300-fps velocity advantage is typical of the .300 Win. Mag., but hunters can likely find hot .280 loads that outperform lighter .300 options.

That additional velocity pans out at extended ranges, too. Both Federal’s Trophy Copper 140-grain .280 and their Trophy Copper 165-grain .300 are travelling about 2,165 fps at 500 yards, but the Win. Mag.’s additional weight gives it 18% more energy at that distance (1,457 ft.-lbs. vs. 1,721 ft.-lbs.).

I usually don’t discuss accuracy in Caliber Battles because “inherent accuracy” is a mostly myth, especially when we’re talking about bottleneck hunting cartridges. But there’s a reason the .280 AI has a reputation for accuracy.

The SAMMI chamber design for the .300 Win. Mag. leaves 0.007 inch of play between the free bore (the portion of the barrel between the chamber and the rifling) and the bullet. The .280 AI chamber design, on the other hand, leaves only 0.001 inch of play in the free bore. Less distance between the bullet and the surrounding free bore helps ensure proper bullet alignment and contributes to greater accuracy.

Of course, a gunsmith can build a custom .300 Win. Mag. that corrects this potential problem, and hand loads can also compensate for the SAMMI chamber design. But in factory rifles with factory ammo, you’re more likely to find a dead-nuts accurate .280 AI than a .300 Win. Mag.

Theoretical greater accuracy isn’t enough to push the .280 AI above the .300 Win. Mag., however, so this one goes to the magnum cartridge.

Winner: .300 Win. Mag.

Shootability We define “shootability” as comfort and cost: How much does each cartridge hurt your shoulder and your wallet?

The argument for less powerful cartridges often relies on the human end of the cartridge combustion. The .280 AI might not hit as hard as the .300 Win. Mag. down range, but it doesn’t hit the shooter's shoulder as hard either. A well-placed shot with a less powerful cartridge is always better (within reason) than a missed shot with a thunderbolt. Since recoil can significantly affect shot placement, sometimes a smaller cartridge is the way to go.

That certainly applies in this matchup. Using a 150-grain bullet and an 8.5 lb. rifle, a .300 Win. Mag. delivers a whopping 23 ft.-lbs. of energy at the shoulder. The .280 AI, on the other hand, only produces 16.2 ft.-lbs. of recoil energy using the same bullet and rifle weight. Many experts say that hunters start to notice discomfort around 20 ft.-lbs. of energy, though this obviously depends on the individual.

Ammunition costs between the two cartridges are similar, but manufacturers often offer cheaper options in the .300. Federal’s Trophy Copper .300 Win. Mag. is $66 for a box of 20 while their .280 AI is $70. But Federal also offers eight times more .300 Win. Mag. options than .280 AI, some of which cost significantly less.

So, if you’re looking exclusively for high-quality hunting ammo, it’s a draw. If you’re looking for less expensive ammunition, you’ll have more luck with the .300.

I don’t think that’s enough to give the Win. Mag. a win here, so I’m giving this round to the .280.

Winner: .280 Ackley Improved

Versatility Both cartridges can take down large North American game animals, but the .300 Win. Mag. will probably do it more easily. Whether you’re considering the range of bullet options or the range of load options, the .300 Win. Mag. is the clear choice. Federal offers 24 Win. Mag. loads using bullets ranging from 150 grains for medium-sized game to 215 grains for large game. The range of .280 AI offerings is more limited, with bullets ranging between 140 grains and 168 grains.

The same disparity applies if you branch out to all manufacturers. The reference book “Cartridges of the World” lists seven load options for .280 AI with bullets ranging from 120 to 170 grains. For the .300 Win. Mag., there are 16 load options with bullets between 110 and 220 grains.

Rifle options favor the Win. Mag., too. Cabela’s lists two varieties of rifles chambered in .280 AI, both high-quality (read: expensive) bolt guns. The Win. Mag. comes in 40 varieties of bolt guns from a range of manufacturers. Most rifles in the Weatherby Vanguard line (including the MeatEater Edition) come in .300 Win. Mag., but if you want the .280 AI, your four options are the Mark V Backcountry, Backcountry Ti, Camilla Deluxe, or the Camilla Ultra Lightweight.

A greater range of bullets and rifles gives the .300 Win. Mag. the clear victory in this category.

Winner: .300 Win. Mag.

And the Winner Is… I’m much more intrigued by the .280 AI—it appeals to the part of me that wants to get off the beaten path. But we follow the science around here, and I can’t argue with better ballistics, greater versatility, more factory bullet options, and way more rifle availability.

If you’re recoil sensitive or looking for something a little different, the AI is an excellent option. But the .300 Win. Mag. is a better all-around cartridge, and it’s hard to argue with a nearly 60-year track record.

Overall Winner: .300 Win. Mag.