M4A1/MK18 Modified Upper Receiver Group (MURG) and 6.8mm Evaluation
At the request of U.S. and foreign military, law enforcement, and special operations forces deployed in the GWOT, TSWG procured and evaluated commercial off-the-shelf (COTS) 6.8x43mm Remington SPC (.270 caliber) drop-on U.S. M4/16-style upper receiver groups and commercial ammunition performance with government off-the- shelf (GOTS) M4/M16-style weapons to address documented combat failures of 5.56x45mm NATO small arms and ammunition. Standard issue 5.56x45mm NATO M855 ammunition is designed for rifles and machine guns with barrel lengths greater than 18". The short-barreled U.S. M4 Carbine (14.5") and MK18 CQBR (10") exhibit unpredictable and relatively poor wound ballistics, terminal effects, and incapacitation/lethality on threat personnel targets and barriers because of the reduced striking velocity and effects on target. Prospective MURG users desired enhanced terminal effects, improved accuracy and increased barrier penetration on target from concealable rifle-caliber small arms often required when operating from mobility platforms or conducting Close Quarters Battle operations. TSWG sponsored a six-month joint interagency project that assessed test articles from nine commercial vendors during 22 test phases. The project demonstrated that select COTS 6.8x43mm Remington SPC MURGs can be installed on GOTS M4 Carbine lower receivers by operators in the field quickly and without tools for an immediate, considerable increase in projectile weight, surface area, and on-target terminal performance. The 6.8mm MURG offers improved combat capability and user survivability over comparable 5.56mm platforms. Several MURG platforms met over 95% of established threshold and objective performance specifications. Test data from this project supports 6.8mm platform fielding in some of the participating organizations. Select COTS MURG hardware and ammunition has preliminary U.S. DoD JAG approval for fielding and is available from various commercial vendors. A restricted distribution report is available to approved personnel by contacting us through the Contact Information Form.