6.8 SPC

6.8×43mm Remington SPC
6.8 SPC (left), .223 Remington (right)
Production history
Designer	Remington Arms, USSOCOM
Designed	2002–2004
Specifications
Parent case	.30 Remington
Case type	Rimless, bottlenecked
Bullet diameter	0.277 in (7.0 mm)
Neck diameter	0.298 in (7.6 mm)
Shoulder diameter	0.402 in (10.2 mm)
Base diameter	0.421 in (10.7 mm)
Rim diameter	0.422 in (10.7 mm)
Rim thickness	0.049 in (1.2 mm)
Case length	1.667 in (42.3 mm)
Overall length	2.260 in (57.4 mm)
Case capacity	34.8–36.9 gr H2O (2.26–2.39 cm3)
Maximum pressure (C.I.P)	58,700 psi (405 MPa)
Maximum pressure (SAAMI)	55,000 psi (380 MPa)
Ballistic performance
Bullet mass/type Velocity Energy 7.45 g (115 gr) fmj 2,575 ft/s (785 m/s) 1,694 ft·lbf (2,297 J) 7.78 g (120 gr) sst 2,460 ft/s (750 m/s) 1,612 ft·lbf (2,186 J) 7.1 g (110 gr) Sierra Pro Hunter 2,500 ft/s (760 m/s) 1,525 ft·lbf (2,068 J) 5.5 g (85 gr) Barnes TSX with "tactical" factory SSA load 3,070 ft/s (940 m/s) 1,780 ft·lbf (2,410 J)
Test barrel length: 410 millimetres (16 in) Source(s):

Test barrel length: 410 millimetres (16 in)

The 6.8 mm Remington Special Purpose Cartridge (aka 6.8 SPC, 6.8 SPC II & 6.8×43mm) is a rimless bottlenecked intermediate rifle cartridge that was developed by Remington Arms in collaboration with members of the U.S. Army Marksmanship Unit, United States Special Operations Command to possibly replace the 5.56 NATO cartridge in a Short Barreled Rifle(SBR)/Carbine.

Based upon the .30 Remington cartridge, it is midway between the 5.56×45mm NATO and 7.62×51mm NATO in bore diameter and muzzle energy. It uses the same diameter bullet (not usually the same weight) as the venerable .270 Winchester hunting cartridge.

The 6.8mm SPC cartridge was designed to address the deficiencies of the terminal performance of the 5.56×45mm NATO cartridge currently in service with the U.S. Armed Forces. The cartridge was the result of the Enhanced Rifle Cartridge program. The 6.8 SPC (6.8×43mm) was initially developed by MSG Steve Holland and Chris Murray, a United States Army Marksmanship Unit gunsmith, to offer superior downrange lethality over the 5.56 NATO/.223 Remington in an M16 pattern service rifle with minimal loss of magazine capacity and a negligible increase in recoil. The goal was to create a cartridge that would bridge the gap between 5.56 mm and 7.62×51mm NATO.

The program started the design by using a .30 Remington case, which was modified in length to fit into magazines that would be accommodated by the magazine wells of the M16 family of rifles and carbines that are currently in service with the U.S. Armed Forces.