It is no secret that many of our military rifle cartridges have gone on to become our most beloved hunting cartridges as well; the .45-70 Government, the .30-06 Springfield, the .308 Winchester and .223 Remington come quickly to mind. But just as you can trace the evolution of our military ammunition from the .45-70 of the 1870s to the .223 Remington (5.56 NATO in its military form) of the 1960s, things continue to evolve.
Hornady’s 6mm ARC (Advanced Rifle Cartridge) is an example of a military cartridge which is equally at home in the hunting field. Based on the 6.5 Grendel—which in turn is based upon the .220 Russian—the 6mm ARC was designed to deliver a performance level better than that of the 5.56 NATO, in a cartridge which is lighter than the 7.62 NATO, having an effective range out beyond 1,000 yards. While the 6.5mm cartridges have been extremely popular over the last two decades, the 6mm bore diameter can be nearly equally effective, if coupled with a barrel which has a twist rate capable of stabilizing those long, heavy-for-caliber bullets that work so well at long ranges.
Using the 6.5 Grendel’s case head diameter of 0.441 inches—making it easy to use a common bolt face dimension—the 6mm ARC is a natural fit for the AR-15 platform. To fit in the existing magazines, a cartridge overall length of 2.260 inches is adhered to, though the case measures only 1.490 inches, allowing for plenty of room outside the case mouth for a long, high B.C. projectile. Being a rimless case, the 6mm ARC relies on the 30-degree shoulder for headspacing, and the cartridge features a neck measuring 0.234 inches—just under the oft-desired one caliber in length to assure proper neck tension, though that fact doesn’t seem to pose a problem in any way.
The primary load for the 6mm ARC is the 108-grain Hornady ELD Match bullet at a rather sedate muzzle velocity of 2,750 fps; though the .243 Winchester, 6mm Remington and 6mm Creedmoor can all better that velocity figure, they're all harder on barrels. It is estimated that the 6mm ARC’s barrel will give a 5,000-shot lifespan. That barrel uses a 1:8 twist rate to stabilize the longer, heavier bullets—the 243 Winchester uses a 1:10 or 1:12 twist—and that is part of the cartridge’s allure; much like the 6.5 Creedmoor, the 6mm ARC uses a high B.C. at a moderate velocity to attain best downrange performance.
I look at the 6mm ARC as a dual-, if not triple-purpose, cartridge for the fact that it can easily deliver the kind of accuracy that a target shooter will appreciate, yet offers two loads for the hunter: the 103-grain ELD-X bullet at 2,800 fps in the Precision Hunter ammo line, and the 80-grain ELD-VT at 3,020 fps in the V-Match line. Looking at the 103-grain ELD-X, you’ll see a listed G1 B.C. of .512; this far exceeds any bullet loaded by Hornady in the .253 Winchester and 6mm Remington. This load—when zeroed at 200 yards—shows a rise of 1.8 inches at 100 yards, dropping 7.6 inches at 300 yards, and 21.8 inches at 400 yards; at the latter distance that ELD-X retains 1,038 ft.-lbs. of the initial 1,793 ft.-lbs. it had at the muzzle. This load betters the performance of the 100-grain .243 Winchester load from Hornady in a smaller, more efficient cartridge, which is easier on the throat of your barrel.
The 80-grain ELD-VT bullet has a G1 B.C. value of .410; on par with that 100-grain Interlock that 6mm shooters adore, despite the 20-grain difference in weight. The ELD-VT is both a target and varmint bullet, using the AMP bullet jacket specifically engineered to give the frangibility that varmint hunters love; the lighter weight allows for higher muzzle velocities, further enhancing the violent expansion. Like the ELD-X and ELD Match, it uses the Heat Shield Tip which resists deformation in flight to best maintain its B.C. value, and the boat tail helps to resist wind deflection and atmospheric drag. Leaving the muzzle at just over 3,000 fps, the 80-grain load for the 6mm ARC betters the trajectory of the 103-grain load by a couple inches, though it drops under the 1,000 ft.-lb. mark before 300 yards.
For those who wish to take advantage of the wide range of 6mm projectiles, handloading the 6mm ARC is the way to go. Reliable load data is available from Hornady, but please be aware that there are two sets of data: one for the bolt-action rifles and one for the semi-auto gas guns, as the gas guns are held to a lower maximum pressure value.
In addition to the two hunting loads from Hornady, there are two Hornady target loads (the ELD Match and a Hornady BLACK 105-grain boat-tail hollow-point load), and a 108-grain target load from Federal Premium, featuring a sleek Berger bullet.
Many folks say the 6mm is gaining considerable ground on the 6.5mm bore diameter for the appreciable difference in recoil, and the 6mm ARC certainly fits this bill. If you’re in the market for a cartridge which covers a whole lot of ground and checks a bunch of boxes, the 6mm ARC should surely be on your list of candidates. I wouldn’t hesitate to take it afield for deer, and I’ve seen the 6mm ARC print some very impressive groups, making it more than suitable for the target community. Will it catch on and become one of our revered cartridges? Only time will tell, but I will say that this design makes a whole lot of sense.
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