6.8 mm Remington SPC

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6.8 Remington SPC (Left) as compared to the 5.56x45mm NATO cartridge

6.8 mm Remington SPC (or 6.8 x 43 mm) is a new rifle cartridge that was developed for US SOCOM. It is touted as being far superior to both 5.56 mm NATO and 7.62 x 39 mm, as well as being easily adaptable to current 5.56 mm NATO firearms with minimal modifications. The U.S. Army Marksmanship Unit also collaborated in the development of the new cartridge and the Barrett Firearms Company produced the modified upper receiver for the M16, known as the M468. Although the main objective was increased lethality, the new cartridge also displays superior accuracy and ballistic characteristics.

It has ballistics almost equal to the British .280, which is more than 50 years old, but due to improved powders the 6.8 mm has a smaller case. The 6.8 mm SPC (Special Purpose Cartridge) has a muzzle velocity in the 2,400 feet per second (730 m/s) range from a 16 inch (406 mm) barrel using the standard 115-grain bullet. It uses bullets of the same .277" diameter as the popular American hunting cartridge .270 Winchester, lending the possibility of civilian sporting use. It must be noted, however, that the .270 Winchester is most often used with bullet weights of 130 to 150 grains for taking medium game.

1 Performance
- 1.1 Muzzle velocity from a 24 inch barrel
2 See also
3 External links

[edit] Performance

Initially assigned only to U.S. special operations units, the new cartridge was widely praised for its increased accuracy at longer ranges, greater terminal ballistics, and the ability to penetrate obstacles such as cinder block walls when compared to the 5.56 mm NATO cartridge.

When compared to the more powerful and well-established 7.62 mm NATO cartridge, the 6.8 mm falls shorter in all these areas but has less recoil, is more controllable and is more likely to fragment in tissue at close to medium range, creating greater damage to the target. While the 6.8 mm generates around 1,759 ft·lbf of muzzle energy with its 115 grain bullet, the 7.62 mm NATO (M80) launches a 147 grain bullet at 2,750 ft/s for 2460 ft·lbf of energy.

The principal advantage of the 6.8 mm is that it permits firearms designed for the short 5.56 mm to fire a more powerful cartridge.

The round has also seen favorable reviews by hunters, who consider it an excellent medium sized hunting cartridge. Its power, however, is less than the .243 Winchester, which is generally regarded as a marginal deer cartridge. (The .243 generates 1,950 to 2,050 ft·lbf of muzzle energy, depending on the load selected.)

Primary criticism about the 6.8 mm round has centered around its poor long-range (greater than 400 yards) performance compared to the NATO standard 7.62 mm or the competing 6.5 mm "Grendel" round. While the round is generally intended for use at shorter ranges, this handicap has somewhat dampened the initial enthusiasm over the SPC round, and given competitors like the Grendel or improved 5.56 mm rounds an opportunity to compete for acceptance.

It was thought that the cartidge would be ideal for various types of 3-Gun matches, such as USPSA 3-Gun, as it would make the Major Power Factor, but have less recoil than the standard Major PF .308 cartidge. The .223 is scored as a Minor PF. As it turns out, there is no commercially available loading that makes Major for the 6.8 SPC and handloaders attempting to make a Major PF load have run into high pressures. As such, the 6.8 SPC has failed to catch on with 3-Gun competitors, who mostly still use the .223 cartidge in a AR15-based rifle.

[edit] Muzzle velocity from a 24 inch barrel

7.45 g (115 gr) Full Metal Jacket (FMJ): 2,625 ft/s (800.1 m/s)
7.45 g (115 gr) Boat Tail Hollow Point (BTHP): 2,624 ft/s (799.8 m/s)
7.45 g (115 gr) Sierra Match King (SMK): 2,625 ft/s (800.1 m/s)

- Note: Remington revised their original estimated velocity figure of 2,800 ft/s from a 20" barrel, moving it significantly lower to 2625 fps from a 24" barrel. **see link to Remington site below:

Remington Web Page: 6.8 SPC Velocity/Ballistics