USA –-(Ammoland.com)- I love the AR platform. And yes, it is a platform as it’s a design model that allows of near infinite customization.
You can add accessories until your rifle looks like a Pakistani Jingle Truck. More importantly, since the rifle is a platform, you can obtain or build one in a dozen or more different calibers.
One of my favorites is 6.8 Remington SPC. Originally developed as a possible replacement for the 5.56mm by some folks from the U.S. Army Marksmanship Unit, United States Special Operations Command and Remington, the 6.8 cartridge is partially compatible with the standard AR platform.
Like 300 AAC Blackout, the 6.8 Remington SPC was developed in response to complaints about stopping power of the 5.56 mm cartridge, especially when used with shorter barrel rifles. It splits the difference (more or less) between 5.56 mm and .308 while still allowing larger capacity due to case size and lighter weight. As a rough example, think of a standard size AR magazine holding 25 rounds of 6.8 SPC instead of 30 rounds of 5.56 mm. Not a bad tradeoff for the extra oomph you get from each cartridge.
The energy of the “standard” 115 grain projectile traveling at 2,640 feet per second is 1,785 foot-pounds – significantly more than the 1,281 foot-pounds of a 55 grain .223 Remington bullet moving at 3,240 feet per second.
While we’re comparing energy levels, let’s look at some other “similar use” cartridges.
- 5.56x45mm SS109 62-grain: 3,100 fps, 1,303 foot-pounds
- .300 AAC Blackout 125-grain: 2,215 fps, 1,361 foot-pounds
- .308 Winchester, 150-grain: 2,850 fps, 2,704 foot-pounds
- .30-30 Winchester, 150 grain: 2,300 fps, 1,761 foot-pounds
- 7.62x39mm (Soviet), 123 grain: 2,435 fps, 1,619 foot-pounds
- .270 Winchester, 130 grain: 3,160 fps, 2,881 foot-pounds
Cartridge length was limited to be compatible with existing magazines, but specific 6.8 mags have been developed for better reliability and allowance for slightly longer cartridges if desired.
According to The folks at Sierra Bullets, “With the magazine length of the AR at 2.260″, cartridge length was critical. There are now magazines on the market designed specifically for the 6.8 mm SPC to allow them to be loaded out to 2.315.”
The 6.8 Remington SPC is based on a .30 Remington cartridge case, but fires, you guessed it, a 7.035 mm projectile. If you don’t recognize 7.035 caliber, that’s just the metric measurement of the popular .270 which is actually .277 inches diameter. See, there’s that goofy tendency to name cartridges something different from their actual diameter again. Just like a .38 Special being .357 caliber.
In simple terms, think of the 6.8 Remington SPC as a .270 Winchester with a smaller cartridge case and less powder capacity that can be fired in an AR type rifle with correct barrel and bolt.
The interesting thing about 6.8 Remington SPC is the terminal performance down range. With about 200 feet per second more velocity than that famous AK-47 round, it has reach out and touch someone performance out to about 500 yards.
The cartridge case is based on the .30 Remington, which explains the need for a bolt swap when converting a standard AR rifle. Similar to development of 300 Blackout from .223 Remington cases, the 6.8 takes a shortened .30 Remington case and necks it down for the .277 inch bullet.
The beauty of this caliber is increased diameter and bullet weight over .223 Remington, while maintaining big time velocity from an AR platform with its overall cartridge length limitations.
I’ve done a fair bit of reloading and tinkering with 6.8 Remington SPC with stellar results when the right bullet / powder combination is used. While you’ll have to buy 6.8 brass (or make your own from .30 Remington.) .270 projectiles are easy to find even in these times of component shortages.
The 6.8 Remington SPC sweet spot calls for bullets in the 110 grain weight range, although I loaded a variety from 90 grains to 130 grains.
Looking at the spectrum of commonly available commercial rounds, you’ll see offerings in the 110 to 115 grain range at velocities of 2,570 to 2,625 feet per second.
Accuracy and velocity samples
Using only one factory rifle, I can’t really make a definitive statement about accuracy of the cartridge, but I can say, that with the test rifle I used, it was very easy to develop sub-minute of angle loads.
I’ve been using a Rock River Arms LAR 6.8 Remington SPC CAR A4 with a few upgrades, but still equipped with the standard RRA two-stage trigger. I mounted a Weaver Tactical 1-5x optic with a CIRT reticle and used that for all accuracy testing. Velocity was clocked with a Shooting Chrony Beta Master placed 15 feet down range. I used a Blackhawk! Sportster Titan III two part rest so I could get good stability without losing the “feel” of shooting the rifle.
At the light end of the bullet weight spectrum, I tried the Sierra 90 grain Varminter hollow point. With the right dose of IMR 4227 powder, I clocked velocity at an average of 2,546 feet per second. With this load I was able to get consistent 3 shot groups of well less than an inch at 100 yards, with the average being about .87 inches. That’s pretty impressive from a factory AR rifle.
Moving up to slightly heavier stuff, I then loaded some 110 grain Hornady V-MAX rounds with H322 powder. Average velocity was 2,451 feet per second. In the excitement of the moment, I forgot to record the 100 yard group sizes, but my notes indicate that it was “crazy accurate.”
In my highly scientific terminology, this translates to less than one inch groups at 100 yards.
If you’re into accu-plinking, get yourself some 115 grain Sierra MatchKings in .277 diameter. I developed a number of loads using these projectiles with IMR 4895 and H322. Groups with different powder and charge combinations yielded results ranging from a best of .58 inches at 100 yards using H322 to 1.02 inches using an IMR 4895 load. Velocities of the 115 grain projectile loads ranged from 2,165 to 2,249 feet per second.
If you’re more into budget plinking, you can order some pulled bullets, readily available in .270 (6.8 SPC) caliber in the 130 grain range. Even using very inexpensive bullets, abused by some sort of violent bullet yanking process, yielded groups in the 1.3 inch range at 100 yards.
At first I wasn’t sure exactly what got me so fired about the 6.8 Remington SPC cartridge. After some use, and some deep thought, I think it boils down to three things.
I like the power level compared to .223 Remington or 5.56 mm. Whatever your preference for home defense, .223 / 5.56 has limitations if you want to hunt. Whether you buy or reload your own, 6.8 Remington SPC opens up a whole new world of hunting possibilities. Deer, hogs, or containers of Tannerite – whatever floats your boat.
Next, you can suppress it with a commonly available .308 silencer. I just mounted a SilencerCo Specwar 762 on the Rock River Arms rifle mentioned in this article and it works like a champ. I ordered a second muzzle brake so I can instantly move my Specwar 762 from a 300 Blackout rifle to the 6.8 Remington SPC. Obviously 6.8 SPC is only a supersonic round, but the suppressor really makes a difference at the firing line.
The last reason this round got my attention became apparent during the “I can’t find bullets” scare of 2013. .270 is a common hunting caliber, and generally ignored by the tactical crowd. While suitable 5.56 mm and 300 Blackout projectiles were in scarce supply, I never had a problem getting as many .270 / 6.8 SPC bullets as I wanted.
Neat stuff. It’s a fun, accurate and low-recoil cartridge with a whole lot of flexibility.
Tom McHale is the author of the Insanely Practical Guides book series that guides new and experienced shooters alike in a fun, approachable, and practical way. His books are available in print and eBook format on Amazon. You can also find him on Google+, Facebook, Twitter and Pinterest.