In December 2019, the cartridge was announced for non-military usage, along with theSIG Sauer CROSS bolt-action rifle. As a short-action rifle cartridge (cartridges having an overall length of 2.750 inches (69.85 mm) or less), increased internal ballistic performance for its cartridge-case volume is accomplished by applying high gas-pressure.[10] In 2020, it was accepted by theSporting Arms and Ammunition Manufacturers' Institute (SAAMI) as a new rifle cartridge and chambering.[11] In 2022, SIG Sauer announced that it intends to commercially chamber theSIG MCX Spear semi-automatic rifle in .277 Fury.[12]
The cartridge uses a case that is the same length and diameter as the.308 Winchester.[13] It has a very high chamber pressure (maximum average pressure, MAP) of 80,000 psi (551.6 MPa) in the SAAMI standard.[7][13] It also means that the .277 Fury is normally chambered in small arms that are capable of handling the accompanyingbolt thrust safely.
The SAAMI warns that MAP levels greater than 65,000 psi (448.2 MPa) may present an increased risk of unsafe cartridge-case or firearm rupture and thus will require new cartridge-case and firearm designs that depart from traditional manufacturing practices, including the use of materials, construction methods, production lines, and other important design criteria.[7][14][15] On ammunition intended to exceed 65,000 psi (448.2 MPa), SIG uses a "hybrid" cartridge case design. Each "hybrid" case consists of astainless steel base coupled to abrass body via an aluminium lockingwasher.[16][17] Stainless steel has a significantly higheryield strength than brass, allowing the engineers to use higher maximum average pressure (MAP) chamber-pressure levels.[18]
The higher MAP enables a 135 grains (8.7 g) projectile to achieve a muzzle-velocity of 3,000 feet per second (914 m/s) from a 16-inch (406 mm)barrel,[7] compared to 2,750 feet per second (838 m/s) for a 135 grains (8.7 g) projectile in a brass-case reduced-power "practice" load.[2]
SIG's commercial catalogue contains both high-power loads using a hybrid cartridge, and reduced-power "practice" loads using a brass cartridge. Commercial types include:
113 grains (7.32 g) hybrid ball (solid copper) described as "Next Gen Ammunition, Magnum Performance", G1ballistic coefficient (BC) ≈ 0.330. SIG describes this ammunition as the one developed for the US Next Generation Weapon Systems. Only available in 460-round cans or 920-round crates, unlike the others which are sold as 20-round boxes.[1]
135 grains (8.75 g)brass elite ball described as "Elite Match Grade FMJ Ammunition", G1 BC ≈ 0.475. Reduced-power load classified as "practice".[2]
Discontinued 135 grains (8.75 g) hybrid "match grade", G1 BC ≈ 0.488.[17][3] Same published G1 BC as Sierra .277 135 grains (8.75 g) HPBT MatchKing.[19]
Discontinued 140 grains (9.07 g) hybrid "hunter tipped", G1 BC ≈ 0.508.[17][3] Same published G1 BC as Sierra .277 140 grains (9.07 g) TGK GameKing.[19]
150 grains (9.72 g) hybrid hunter described as "featuring NOSLER Accubond bonded core bullets", G1 BC ≈ 0.500.[20]
155 grains (10.04 g) hybrid match described as "featuring Sierra MatchKing HPBT bullet", G1 BC ≈ 0.549.[4]
Do note that ballistic coefficients are somewhat debatable.[21]
SIG Sauer claims that the cartridge has performance superior to the6.5mm Creedmoor, exhibiting 6 to 9 feet (1.8 to 2.7 m) lessbullet drop at 1,000 yards (914 m), while delivering 20 to 25 percent greater energy.[17][7]
US Army award and designation as 6.8 common cartridge
An XM250 automatic rifle with inserted ammunition belt
In January 2019, the United States Army began theNext Generation Squad Weapon Program to find replacements for theM4 carbine andM249 light machine gun. On April 19, 2022, the United States Army announced that it had selected SIG Sauer to build theM7 rifle to partly replace the M4 carbine, while theM250 automatic rifle was to replace the M249 SAW in the LMG role. In both cases it had selected the company's Fury ammunition, utilizing government-provided projectiles and vendor-designed cartridges as the new weapon's ammunition.[22][23]
The M7 was designed to fire the 6.8×51mm SIG Fury cartridge in response to concerns that improvements inbody armor would diminish the effectiveness of the5.56×45mm NATO round used in the M4 carbine and M249 SAW and increase their lethality and effective ranges compared to common, battlefield rounds such as the 5.56×45mm NATO and7.62×51mm NATO.[24][25][26][27]
XM1188 Reduced Range
Operational testing of the M7 rifle, XM250 automatic rifle, XM157 fire-control optic-platform unit, and the 6.8×51mm ammunition squad-weaponry is expected to begin in 2024. However, this does not guarantee actual, widespread future issue.[28] The military designation for this round is6.8 common cartridge.[6] TheXM1186 is the general-purpose 6.8 mm round, with other versions including reduced-range rounds so that weapons chambered in 6.8 mm can fire on existing ranges designed for the 5.56 mm, marking rounds for force-on-force shooting, andblank andtracer rounds.[29]
As of March 2022, the United States Army has a solicitation ongoing for anM240 machine gun 6.8×51mm conversion kit for the 7.62×51mm NATO-chamberedM240B andM240L general-purpose machine guns.[28][30]
^ab"PE 0603639A: Tank and Medium Caliber Ammunition FY2021"(PDF).he Next Generation Squad Weapons (NGSW) ammunition is split into two initial variants, the General Purpose (GP) and the Special Purpose (SP). The nomenclature for the GP ammunition is XM1186 and the nomenclature for the SP ammunition is XM1184.
^ab"LIGHTEN UP".www.army.mil. 6 June 2024.. Both XM1186 and XM1188 feature a hybrid metal case design consisting of a brass body and steel head, reducing cartridge weight by more than 20% compared with a brass-cased equivalent cartridge.
^ab"Small Arms Ammunition | www.dau.edu".www.dau.edu.AIN 006-24, INFORMATION AND NEW NSN/DODIC FOR CARTRIDGE, 6.8 MM: GENERAL PURPOSE, XM1186, CARTRIDGE, 6.8 MM: REDUCED RANGE (RR), XM1188, AND CARTRIDGE, 6.8 MM: BLANK, XM1192 NEW
