More juice from the lemon?
Warm, sunny midday, we were tootling around Zack Aultman’s place in southern Georgia in a four-wheeler. A decent-sized boar jumped up on the forest verge and started jinking across a clear-cut, running at top speed like a champion broken-field runner. Zack was driving and there was an AR-15 between us. I knew it had a loaded magazine in the well, but I was a second slow on the uptake and the pig had already covered some ground before I got the rifle charged and up. The first shot felt good, but I guess the pig zig-zagged out of the way because there was no apparent effect.
I lost sight in some brush and figured I’d had my chance—and then the pig reappeared, still in the open and streaking off, now pushing 200 yards. Swinging hard, I got with the pig and a bit ahead. Lucky shots sometimes happen; at the second shot the pig somersaulted in a cloud of dust. The animal had gone down so fast—and so hard—that I assumed I’d broken the spine. Nope, by mysterious coincidence (or the pig’s incredibly bad luck), the bullet had struck center on the shoulder, and there was no exit.
My friend Zack enjoys a long deer season on his place, and has an ongoing problem with feral hogs. He’s also a bit of a rifle addict, so there’s no telling what he might have on hand. Other than to verify it was a “normal” AR with empty chamber and cartridges in the magazine, I hadn’t looked closely at the rifle when Zack handed it to me. Considering hogs are always in season and, knowing Zack, I assumed it was reasonably zeroed. Now we both paused and took a closer look, because the way this little rifle flattened that hog was impressive.
Look, maybe that was a fluke…like my shot. No two animals react exactly alike upon receiving a bullet, and flukes can be both good and bad. So, when evaluating cartridge and bullet performance on game, it’s risky to make assumptions based on limited exposure. I make no definitive claim, but terminal performance gave us pause. The rifle was from Arrow Arms in nearby Macon, Georgia, and the cartridge was their proprietary .308 Arrow, propelling a 125-grain jacketed hollowpoint at 2814 feet per second.
There’s nothing magic about those numbers, slower than a .308 Winchester, also faster, and yielding more energy at 200 yards, than anything else I’ve shot out of an AR15 platform. The AR10 was developed for the 7.62×51 (.308 Winchester) cartridge. In the late 1950s, Gene Stoner and his team the AR10 scaled down the AR10 to create the AR15, lighter, handier, and intended for smaller, less powerful cartridges. The .223 Remington was essentially a parallel development, created in 1957 to fit the AR15 action.
Remington released the .223 Remington as a sporting cartridge in 1963, and in 1964 both the .223 (5.56mm) and M16 were adopted by the U.S. military. The .223 quickly became a popular varmint and target cartridge, but decades would pass before semiautomatic sporting versions of the AR15 achieved widespread popularity. During most of those decades, the AR15 and the .223 Remington (after 1980, 5.56x45mm NATO) were inextricably linked, with few other options.
During the last 20 years, much effort has been expended developing cartridges that increase, or significantly alter, performance from an AR15 action. Cartridges are often developed for specific actions…especially popular actions. And, most rifle actions have limitations. Over decades, Winchester developed several cartridges for their 1894 lever-action. Most were based on the .30-30 case because the ’94 needs a rimmed case…and the action has both pressure and cartridge dimension limitations.
Even the versatile bolt-action has restrictions. Classic and current bolt-actions like the 98 Mauser, Winchester Model 70, Remington Model 700, and Savage 110 can be adapted to a wide range of cartridges, but cannot house the largest cartridges like the .338 Lapua and .378 Weatherby family (although there are extra-large bolt-actions that can).
Action length is always a consideration. As a detachable-magazine rifle with integral magazine well, the AR15 action is limited to cartridge length of 2.275 inches. This is a short centerfire rifle cartridge. Cartridge overall length specification is 2.825 inches for the popular 6.5mm Creedmoor. The Creedmoor (and the entire .308 Winchester-based family) fits easily into the AR10 action (because that’s the cartridge size it was designed for), but you simply cannot house that size of cartridge or that level of power into an AR15 action.
There’s only so much juice to squeeze from a lemon. However, because of the incredible popularity of the platform, a lot of cartridges have been developed to squeeze just a bit more juice from the AR15. Cartridge length is the primary limiting factor. The .223 Remington case can be necked up or down, changing bullet diameter and weight, which dictates potential velocity. The .223/5.56mm rim diameter is .378-inch. Without altering bolt face, this is also a limitation, and you can’t alter the case shape much without going to cartridge-specific magazines.
Among others, the very fast .17 Remington is the .223 case necked down; the .300 AAC Blackout is the .223/5.56mm shortened and necked up, but designed so standard 5.56mm magazines can be used. The AR15 action can handle a wider or fatter case, which increases powder capacity. Winchester’s .350 Legend retains the .378-inch rim and, at 2.25 inches, is short enough. However, the rim is rebated (smaller than the base), and the base diameter is larger (.390 inches). Wider cases with rebated rims are also how they cram the .30 Remington AR and .450 Bushmaster into the AR15 action. Both of these use a rim diameter and bolt face of .473-inch, same as the .30-06. Performance is amazing from the little AR15 action. However, magazines must be modified (with a single-stack follower), and magazine capacity is greatly reduced.
It’s probably not a coincidence of design that the AR15 action easily houses the 2.2-inch 7.62x39mm Russian. Propelling a 123-grain bullet at a bit over 2400 fps, the 7.62 Russian is obviously a long-proven military cartridge. It’s also a pretty good hunting cartridge, effective on deer and hogs at short to (very) medium range, with performance on game on par with the .30-30 (which is not damning with faint praise). With rim diameter of .447, the standard .223/5.56mm bolt face won’t work, and specific magazines are required, but the 7.62mm Russian is a fairly common and popular AR chambering. The 6.5mm Grendel, which I like very much, is simply the 7.62x39mm case necked down with body taper removed. It is much faster, propelling a 123-grain bullet 2650 fps. Now 20 years old, the 6.8mm SPC Remington is another option. Designed as a military cartridge to offer better terminal performance than the 5.56×45 yet with minimal reduction in magazine capacity, the 6.8 SPC is also an effective short to (very) medium range hunting cartridge. Based on the old .30 Remington, the 6.8 SPC has rim diameter of .422-inch. Although never widely adopted by the military, the 6.8 has its fans, but I never warmed up to it.
As a hunting cartridge, I considered the 6.5mm Grendel one of the most versatile options for an AR, and still do. Then, by chance, I ran into the .308 Arrow. It is nothing more, nor less, than the 7.62mm Russian case, blown out to remove body taper, with sharper shoulder, but retaining the .30-caliber bullet. It is thus essentially an “improved” version. A proprietary of Arrow Arms (www.arrowarms.net), the improvement is considerable, with Hornady offering cases and dies. Arrow Arms loads are rated: 125-grain bullet at 2814 fps; 130-grain bullet at 2739; and 150-grain bullet at 2545 fps. This is still far short of .308 Winchester velocity; that’s just not possible from the AR15 action. However, these are very credible velocities: Much faster than the .300 Blackout, 7.62 Russian, or .30-30, and in the ballpark with the .300 Savage (also not damning with faint praise).
Unlike many of the AR cartridges, the .308 Arrow was not designed as an alternative military cartridge, nor for use with suppressor; it was designed as a hunting cartridge, to wring maximum .30-caliber performance from the AR15 platform. Again, it’s dangerous to reach conclusions based on limited exposure. However, like so many Americans, I believe in .30-caliber performance…and I believe in at least moderate velocity. We probably have all the cartridges we need (maybe too many), so I don’t predict huge popularity for the .308 arrow. Even so, it’s a sound cartridge that really does squeeze a bit more juice out of the AR platform. I’m going to spend a bit more time with it.