When .223 just isn’t enough…
Contrary to that provocative opening line, I’m not going to embark on a “Nyah, nyah, nyah, this caliber is more betterer or less betterer than some other caliber” tirade. Instead, I’m going to take this opportunity to celebrate diversity. You know, like hippies.
One of the reasons that the AR or MSR (Modern Sporting Rifle) platform is so insanely popular is because it’s so darn flexible—more flexible than even White House Spokesperson Jay Carney at an Obamacare press conference. It’s not only flexible in terms of fit (with adjustable stock options) and accessorizing (with everything from tactical lights to chainsaws), it’s flexible in terms of caliber.
Somehow or another, I got a bug up my backside to try out an AR rifle in 6.8mm Remington SPC and I chose the Rock River Arms (RRA) LAR-6.8 6.8mm Remington SPC CAR A4. Why? Well, for no good reason other than I wanted it. That and the fact that I live in ‘Murica.
What exactly is 6.8mm Remington SPC, you ask? It’s a proposed solution to “stopping power” complaints surrounding the 5.56x45mm military round. It’s not as heavy and bulky as the 7.62x51mm (.308 Winchester) cartridge, so one can carry plenty of ammo. It was designed for improved short-barrel performance via a joint effort between US Special Forces, the Army Marksmanship Unit, and Remington. Splitting the difference between 5.56 and 7.62, it’s easily adaptable to AR rifles by swapping the bolt, barrel, and magazine for 6.8 SPC versions of said parts. As it shares the same overall length as the 5.56 round, no changes to the AR lower receiver are required. Its cartridge case is derived from the .30 Remington, so unfortunately you can’t make your own brass from scrounged-up .223 casings. As a side note, unlike the .223/5.56, 6.8 SPC uses a large rifle primer.
Features of the Rock River Arms 6.8 SPC CAR
Rock River Arms makes a fine AR. A few years back, the DEA ordered 3.2 truckloads of them and some units of the FBI and US Marshals piggybacked onto that contract. Since that time, the RRA models have earned a solid reputation.
If you order your rifle in advance instead of buying one off-the-shelf, you can customize it to your heart’s content and a rifle will be built according to your specifications. Some of the options available include:
- A2 or A4 upper receiver.
- Chrome moly or chrome-lined barrel.
- Various flash hiders: want a Smith Enterprise Vortex or muzzle brake? No problem.
- Gas block/sight base: standard, low-profile, or flip-up-ready versions are all available.
- Standard or ambidextrous safety levers and magazine catches.
- Handguards, grips, and buttstocks: too many options to list here.
- Trigger guards and bolt handles are also customizable for normal or gloved use.
For this review, I specifically ordered the 6.8 SPC CAR with an A4 upper receiver, the RRA Quad Rail Free Float handguard, a chrome-lined barrel, a gas block sight base, a Smith Enterprise Vortex Flash Hider, and Badger Tactical Bolt Latch. Designed as an optics-ready rifle, this version is a bit of a Cadillac.
Everything on this rifle is snug and tight-fitting. The safety lever operates smoothly, but with positive engagement and no slack. The trigger is an RRA two-stage design. I found the take-up stage to be ever-so-slightly gritty at first, but that smoothed out with use. It’s not light in pull weight, but the trigger break is crisp and sure. It’s a combat trigger, not a match trigger, so be aware of that if you’re looking for a competition gun.
I particularly like the handguard. The RRA Quad Rail is a free-floated design that features a rock-solid mount to the upper receiver. And I mean rock-solid. The handguard is round with full-length rails machined on all four sides. The rounded portions between rails are filled with small ventilation holes. I’m sure these also help to reduce weight of the handguard. While on the free-floated topic, the low-profile front gas block has about 1/32-inch of clearance so it does not interfere with the handguard either. The gas block has a rail that can be used for a back-up iron sight, just be aware that it sits about a quarter-inch lower than the handguard rail.
This model includes metal sling loops on the base of the buttstock and the base of the gas block. The placement is good for a two-point sling, but as a personal preference, I would probably move the front sling mount to the handguard so I could snug it up tight for longer shots without putting pressure on the barrel.
Magazines are not exactly interchangeable with standard .223 AR magazines. Due to the larger case size, the standard capacity of a 6.8 SPC magazine is 25 rounds instead of 30. If you shop, you can find magazines of greater or lesser capacity. For example, the five-round magazine I tested turns the RRA 6.8 SPC CAR into a swell hunting rifle. Now that the magazine scare of 2013 is winding down, you can find 6.8 SPC magazines without too much heartache.
Like, what’s its energy vibe, man?
While it uses the same projectile diameter as .270 Winchester, the 6.8 SPC cartridge is a lower-energy offering than nearly all .270 loads. That’s simply due to case capacity limitations. The 6.8 SPC was designed to fit into a standard AR-platform gun without having to change things like magazine well dimensions.
The “classic” 6.8 SPC load uses a 115-grain, .277-inch diameter projectile, and will clock in around 2,640 feet per second. This produces a muzzle energy of 1,785 foot-pounds. But what on earth does that mean? Foot-pounds are just one energy measure of a bullet’s effective power. While it’s an inexact comparison, it does provide some indication of relative “oomph” of one cartridge compared to another. To put the “oomph” of the 6.8 SPC in real terms, let’s consider the following analogy.
Assume you have a 135-pound hippy. Yes, I know, he needs more protein in his diet. Now, using your most creative method, mount an eye bolt to the top of his head, thus enabling you to suspend him like a pendulum. If this hippy is propelled by a tofu fart at exactly 19.9 miles per hour, the hippie impacting a solid object will impart 1,785 foot-pounds of energy to that object. Okay, so maybe that doesn’t tell you too much about 6.8 SPC projectile performance, and building a rifle that fires a hippy at exactly 19.9 miles per hour would be impractical, but it’s a fun analogy that amuses me.
How does the 6.8 SPC stack up to other “similar-role” cartridges in terms of raw energy?
- .223 Remington 55-grain projectile: Muzzle velocity of 3,240 feet per second, muzzle energy rated at 1,281 foot-pounds
- 5.56x45mm SS109 62-grain: 3,100 fps, 1,303 foot-pounds
- .300 AAC Blackout 125-grain: 2,215 fps, 1,361 foot-pounds
- 6.8mm Remington SPC 115-grain: 2,640 fps, 1,785 foot-pounds
- .308 Winchester, 150-grain: 2,850 fps, 2,704 foot-pounds
- .50 BMG, 750-grain: 2,935 fps, 14,342 foot-pounds*
*While the .50 BMG is not comparable to the 6.8 SPC in any practical sense, I couldn’t resist making the comparison. Because…Ma Deuce!
We’re just having a little fun here, but if you really want to learn about cartridges, energy, momentum and other technical things, be sure to check out the Cartridge Comparison Guide. It’s got lots of performance data on the 6.8mm Remington SPC and just about any other cartridge you can think of.
Will it shoot?
Rock River Arms advertises this rifle as a 1 MOA shooter. In plain English, with a rock-solid bench and adequate ammunition, it should fire rounds into a one-inch group at 100 yards. Seeing this as a personal challenge for my reloading skills, I whipped up several custom loads in 6.8 SPC. As this rifle encroaches into “premium” country, I used quality components: brand-new brass and Sierra MatchKing bullets.
This rifle really, really liked 115-grain Sierra MatchKing bullets. My best group was .578 inches at 100 yards. I was also able to keep 90-grain Sierra MatchKing loads within an inch of each other. Not shabby at all for a factory-produced semiauto.
Will it hunt?
I think the AR/MSR platform makes for an ideal hunting rifle. The ability to add a whole slew of upper receivers to a standard lower allows for near-infinite caliber choice. From .22 Long Rifle to .458 SOCOM, you’ve got plenty of choices for all types of game. I’ve even seen a crossbow AR upper, although admittedly, that’s a little weird.
Having introduced lots of folks to shooting, I’ve found that “scary” adjustable stock is no more than a great way to perfectly fit a rifle to just about any shooter—men, women and youth. The semiautomatic action makes for light recoil even though the rifle itself is fairly light.
As the magazine is detachable, you can easily use a low-capacity version for better maneuverability—and to adhere to any magazine-capacity hunting restrictions that might exist in your locale.
Just for kicks, I loaded some 130-grain pulled bullets. As “pulled” bullets are literally yanked out of unused cartridges and sold cheap, they’re not the most accurate. Even with these, I was easily able to shoot 1.3-inch groups at 100 yards. Using proper game bullets or pre-loaded hunting ammo will most certainly yield better results.
This rifle was a pleasant surprise. It’s the first time I’ve shot the 6.8mm Remington SPC cartridge—and I liked it. Recoil is hardly more substantial than the .223/5.56 round and as the targets indicate, the RRA 6.8 SPC CAR can shoot. To me, whether it’s a replacement for .223/5.56 is irrelevant—it’s simply another option to consider. It’s a handy, easy-to-shoot rifle that further expands the capabilities of an AR rifle. Target shooting? Sure. Hunting? Sure. Self-defense? Sure. The only drawback is availability of 6.8 SPC ammo. It’s not nearly as common as .223 or 5.56. If you choose to reload, ammo availability doesn’t matter as the .277 projectiles are everywhere. Will it catch on in the commercial market? Time will tell.
Images by Tom McHale