Advances in AR-15 Ammo

Some doubt that an AR-15 can be used for game as large as this 200-plus pound black bear. However, Remington’s .30 AR cartridge has taken the AR-15 to the next level, with ballistics that match that of the legendary .300 Savage cartridge.

Some doubt that an AR-15 can be used for game as large as this 200-plus pound black bear. However, Remington’s .30 AR cartridge has taken the AR-15 to the next level, with ballistics that match that of the legendary .300 Savage cartridge.

Big-Bore ARs

At varying points in the last decade, several enterprising souls looked into an AR magazine and thought to fill it up completely with one massive cartridge instead of a couple little ones. The resulting cartridges—the .450 Bushmaster, .458 SOCOM, and .50 Beowulf, among others—are big league heavy hitters.

They all use a rebated rim to fit inside a standard AR bolt head and generally run at pressures well below that of the 5.56mm. The only real concern with fitting cartridges of this size in an AR resides in the bolt thrust and making sure the gas port is both the right size and sits in the right place for reliable function. All three rounds obviously produce substantially more recoil than 5.56mm rifles, but the rifle seems up to the task. (Scope mounts are another matter.)

Rifle manufacturers seem to have divvied up the calibers between themselves, with Rock River Arms building .458 SOCOM rifles, Bushmaster producing the .450 Bushmaster, and Alexander Arms building rifles chambered for the cartridge it invented. Ammunition is a little hard to find and, in some cases, expensive, but available. Reloaders usually prefer the SOCOM over the Bushmaster and Beowulf, because the wider selection of available bullets.

The .458 and .50 were envisioned as interdiction and barrier-beating rounds for stopping cars at roadblocks and ventilating two-legged predators hiding behind cinderblock walls and the like. It seems most shooters use these big-boress to turn mobile pork into stationary pork. The rounds are also ideal for close-range bear hunting or hitting anything with bullets weighing in excess of 250 grains and moving over 2,000 fps. Most Beowulf loads produce over 2,900 foot-pounds (ft-lbs) of muzzle energy.

Imagine the possibilities of combining one of these big-bore cartridges loaded with good, solid bullets and a lightweight AR carbine fed from a high-capacity detachable magazine. Pair the rifle with a weapons light and a 1X-optic like an Aimpoint, Trijicon, or EOTech, and you might have the perfect guide’s gun for backing up hunters or tracking wounded bears in Alaska. It weighs less, provides more firepower, and permits faster follow-up shots than most other rifle actions.

4 thoughts on “Advances in AR-15 Ammo

  1. capta45capta45

    “Slower 1:7 twist rates” – quite certain you meant either ‘slower velocity bullet’ or ‘faster 1:7 twist rates’. Obviously a 1:7 twist rate is faster than a 1:9 twist rate and will produce more rotation. Longer bullets generally need a faster twist rate to properly stabilize.

  2. retired75th

    There is a concerted ongoing effort to “sell” the 5.56. An effort to get the 5.56 to do what it is not cable of doing. If the platform, such as the AR and its variants was not so versatile, the AR in 5.56 would be a dying breed. It is the flexibility of the AR and not the 5.56 that sells the firearm. This is the bottom line. If you are engaging targets at 500 to 600 yes, are you seriously going to rely on 5.56? Of course not, so why push an inadequate round, except to make money. . There is a big difference between hitting the bulls eye on a paper target at 500 yds, and killing the enemy at 500 yds. If you are hooked on the AR, which is a good weapon, and want to engage real targets at extended range at least rebarrel the weapon. No firearm is the ideal for all missions and conditions, so base weapon selection on the mission, and not hype from folks with a financial angle. And one last thing, in what states is it legal to take big game with 5.56 as the author states?

    1. 454lvr

      Texas and Oklahoma are two that I know of that allow 223 to be used for deer. Oklahoma requires a 7 round or less magazine in the 223. If the ar is of the 308 variety you can used the 20 round magazine.

  3. Harold

    If you’re sticking to .223/5.56 mm, consider rounds that use Barnes TSX copper bullets. Black Hills makes loadings in both .223 and 5.56 mm, the latter to NATO and military specs, sealed, low flash powder and all that. They also sell to us their MK262 Mod 1 that you mention.

COMMENT