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by Bryce M. Towsley – Wednesday, June 22, 2016

https://www.americanrifleman.org/articles/2016/6/22/big-bore-ar-cartridges/

When it comes to dispatching game with authority—and a single shot—nothing gets the job done quite like the big, heavy bullets available in chamberings such as these three, which all fit in a standard AR-15-size platform.

I have a simple test when considering cartridges for hunting big game with an AR-15-style rifle. It simply requires honestly answering the question: If you were shopping for a non-AR rifle to hunt deer, bear or hogs would you pick one chambered for the cartridge you are willing to use in an AR-15? In other words, would you choose a bolt-action deer rifle chambered for .300 Blackout over say a .308 Win. or a .30-’06 Sprg.? The answer, of course, is no. Otherwise gunmakers would be flocking to build .300 Blackout bolt-action rifles. Why aren’t they? Because there just isn’t much of a market. As an example, Remington did introduce a bolt-action in 6.8 mm SPC, but has since dropped it due to poor sales.

The .223 Rem. is a good seller in a bolt-action hunting rifle, but not for big game. The vast majority of .223 Rem. bolt-action rifles are purchased for hunting varmints. The few .300 Blackout bolt-action rifles I have seen are designed for tactical use and to be used suppressed—not for deer hunting.

Big-game hunters use the .300 Blackout, 6.8 mm SPC or .223 Rem. in AR-15s because of the platform, not the ballistics. Sure, they can all kill game, but I’d argue that they make shot placement even more critical than more powerful cartridges traditionally used to hunt deer, bear or hogs.

The trouble with the AR-15 platform is the limitations it puts on cartridge length. It’s hard to make the gun work with a cartridge much longer than 2.26″. Of course, you can move up to the larger AR-L (AR-10) platform that is based on the .308 Win.-size cartridges, but the guns are bigger, heavier and more expensive.

Oddly enough, back in the early days of self-contained metallic cartridges, new cartridge designers faced a similar dilemma, but for very different reasons. The combination of blackpowder and early bullet construction limited velocity to around 1,500 f.p.s., give or take. So, to increase power, the cartridge designers made the bullets heavier and bigger in diameter. That’s why the military’s rifle cartridges were .45-caliber in the 1870s rather than the .22 caliber used today.

Today’s hard-hitting hunting cartridges for the AR-15 use the same concept. If you can’t make the cartridge longer, then make it larger in diameter and add some bullet weight.

Just as the hunters using the old blackpowder cartridges understood, a big-diameter, heavy bullet at moderate velocity is deadly on big game.

The lineup of big-bores is not huge for the AR-15 platform. In fact, from mainstream gunmakers there are only three cartridges. But that’s enough, as each member of this trio brings something impressive to the table.

.450 Bushmaster
This is the smallest of the thumpers, with a bullet diameter of .452″. It uses a rebated rim cartridge case based on the .284 Win. case.

The concept behind what would become the .450 Bushmaster was initially put forth by Col. Jeff Cooper. Cooper is best known for creating the “Modern Technique” of handgun shooting and for his admiration of the M1911 pistol. But Cooper was also an avid hunter and loved to roam wild places in a “come what may” sort of way. He was a man of great experience, having hunted all over the world, and he recognized that a big bullet is a good thing when shooting big game. He thought that the perfect rifle for most “general” big-game hunting would be a semi-automatic of larger than .44 caliber that was capable of taking big game out to 250 yds. He called this the “Thumper” concept.

As with other “thumper” loads for the AR platform, the .458 SOCOM feeds from the conventional AR magazine as if it were a single-stack.

.458 SOCOM
The .458 SOCOM was developed for military applications after the fighting in Mogadishu, Somalia, in 1993. That battle left a lot of participants disappointed in the performance of the 5.56×45 mm NATO cartridge, and they wanted some serious, .45-70 Gov’t-class thumping power for the M16 and M4 rifles. It’s worth considering that if the guys in the fight don’t think the .223 is enough gun, perhaps we should re-evaluate its use for hunting such animals as hogs, bear, moose and elk—game that often runs bigger and tougher than the average man.

The .458 SOCOM cartridge came out in 2002, and while it didn’t gain widespread acceptance as a military round, it has proven to be a great hunting cartridge. It uses a lengthened .50 AE case with a rebated rim and is necked down for a .458″ bullet. One big advantage with that .458 diameter is there is a wide selection of rifle bullets on the market. This is reflected in the multiple factory load options, and it opens a lot of doors for handloaders. One of the best bullets is the 300-gr. TTSX that Barnes developed specifically for this cartridge.

It might have a military background, but the .458 SOCOM is a big-game cartridge capable of taking anything that walks in North America.