6.8×51mm

The .277 Fury or 6.8×51mm Common Cartridge (designated as the .277 SIG Fury by SAAMI) is a centerfire, rimless, bottlenecked rifle cartridge announced by SIG Sauer in late 2019. Its hybrid, three-piece cartridge case has a steel case-head and brass body connected by an aluminum locking washer to support the high chamber pressure of .

Background

The cartridge was designed by SIG Sauer for the United States Army's Next Generation Squad Weapon Program (NGSW). It is dimensionally similar to the 7.62×51mm NATO service cartridge.

In December 2019, the cartridge was announced for non-military usage, along with the SIG Sauer CROSS bolt-action rifle. As a short-action rifle cartridge (cartridges having an overall length of or less), increased internal ballistic performance for its cartridge-case volume is accomplished by applying high gas-pressure. In 2020, it was accepted by the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) as a new rifle cartridge and chambering. In 2022, SIG Sauer announced that it intends to commercially chamber the SIG MCX Spear semi-automatic rifle in .277 Fury.

Specifications

The cartridge uses a case that is the same length and diameter as the .308 Winchester. It boasts a very high chamber pressure (maximum average pressure, MAP) of in the SAAMI standard. It also means that the .277 Fury is normally chambered in small arms that are capable of handling the accompanying bolt thrust safely.

The SAAMI warns that MAP levels greater than 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. On ammunition intended to exceed , SIG uses a "hybrid" cartridge case design. Each "hybrid" case consists of a stainless steel base coupled to a brass body via an aluminium locking washer. Stainless steel has a significantly higher yield strength than brass, allowing the engineers to use higher maximum average pressure (MAP) chamber-pressure levels.

The higher MAP enables a projectile to achieve a muzzle-velocity of from a barrel, compared to for a projectile in a brass-case reduced-power "practice" load.

Ammunition types

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:
* hybrid ball (solid copper) described as "Next Gen Ammunition, Magnum Performance", G1 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.
* ''brass'' elite ball described as "Elite Match Grade FMJ Ammunition", G1 BC ≈ 0.475. Reduced-power load classified as "practice".
* Discontinued hybrid "match grade", G1 ballistic coefficient (BC) ≈ 0.488. Same published G1 BC as Sierra .277 HPBT MatchKing.
* Discontinued hybrid "hunter tipped", G1 BC ≈ 0.508. Same published G1 BC as Sierra .277 TGK GameKing.
* hybrid hunter described as "featuring NOSLER Accubond bonded core bullets", G1 BC ≈ 0.500.
* hybrid match described as "featuring Sierra Matching HPBT bullet", G1 BC ≈ 0.549.

Do note that ballistic coefficients are somewhat debatable.

Performance

SIG Sauer claims that the cartridge has performance superior to the 6.5mm Creedmoor, exhibiting less bullet drop at , while delivering 20 to 25 percent greater energy.

US Army award and designation as 6.8 common cartridge

In January 2019, the United States Army began the Next Generation Squad Weapon Program to find replacements for the M4 carbine and M249 light machine gun. On April 19, 2022, the United States Army announced that it had selected SIG Sauer to build the XM7 rifle to partly replace the M4 carbine, while the XM250 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.

The XM7 was designed to fire the 6.8×51mm SIG Fury cartridge in response to concerns that improvements in body armor would diminish the effectiveness of the 5.56×45mm 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 and 7.62×51mm NATO.

Operational testing of the XM7 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. The military designation for this round is ''6.8 common cartridge''. The ''XM1186'' 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, and blank and tracer rounds.

US Army solicitation

As of March 2022, the United States Army has a solicitation ongoing for an M240 machine gun 6.8×51mm conversion kit for the 7.62×51mm NATO-chambered M240B and M240L general-purpose machine guns.

US ammunition types

* XM1168 General Purpose (Prototype)
* XM1184 Special Purpose.
* XM1186 General Purpose. Hybrid.
* XM1188 Reduced Range. Hybrid.
* XM1192 Blank.

References

External links

New for 2020: SIG Sauer .277 SIG Fury Ammunition
via YouTube
Archive


.277 SIG Fury SAAMI Drawing
(archived), issued 09/23/2020
** Not found in SAAM
Z299.4-2025
standard.

{{DEFAULTSORT:277 Fury
SIG Sauer cartridges
Pistol and rifle cartridges
Military cartridges
Weapons and ammunition introduced in 2019