The Adaptive Combat Rifle was originally developed by Magpul as the Masada, then licensed by Bushmaster LLC for future development and production. Bushmaster was subsequently made part of The Freedom Group by owner Cerberus Capital Management, as was Remington Arms, and both companies have worked to bring ACR from prototype to production.
The ACR is designed with a reliable short-stroke gas piston operating system and is made of lightweight materials to allow the operator to carry more ammunition and/or body armor. Target weight for the US Military-spec rifle is 7 pounds or less (empty). The ACR is an adaptable, modular weapon which comes in several variations and barrel options to conform to the needs of today's military and law enforcement. Unlike classic rifle systems, which must be reconfigured by gunsmiths, or other modular weapons such as the SCAR which still require tools to disassemble, the ACR can be rapidly reconfigured by the user with no extra tools or special training. All components can be swapped quickly and easily, allowing the operator to tailor his or her weapon to the mission at hand. The same rifle can be a close-quarters carbine in one minute and a long-range battle riffle in the next.
Along with the standard NATO 5.56x45mm caliber, the ACR will be configurable to fire alternative rounds popular with Special Forces. Barrels, bolt faces, and magazines to fire the 6.5mm Grendel and 6.8mm Remmington SPC are to be offered, as will the components to fire the 7.62x39mm in widespread use by the AK-47. The latter option will allow ACR uses to use scavenged or picked-up ammunition in hostile territory, or to be used to conduct secretive missions without leaving spent Western ammo around as evidence. Various barrels from 10" up to 18" are to be offered, compatible with various suppressors. Unlike the SCAR, specialized barrels and components to create LMG or Sniper variants are not part of initial plans but may appear later.
The ACR combines design elements of several different assault rifles, from the SCAR's upper-receiver configuration to the heavy use of polymers as in G36. The trigger group are descended from that used by the M-16, and the basic barrel is essentially an AR-15 barrel. Unique features include an adjustable gas system, unique long-life chamber and barrel coatings in place of traditional chroming, the aforementioned modularity, and built-in storage compartments. The rifle makes liberal use of rail mounting systems, allowing several attachments like sights, scopes, forward grips, bipods, laser designators, and grenade launchers. The top rail is a "floating" rail, meaning it is not attached to the barrel and thus the two can be swapped without one effecting the other. Firing rate is estimated to be 600-800 rpm depending configuration.
The ACR is due to be available to military and law enforcement in 2010. A semi-auto only version with 16" barrel is to be available for civilians in 2010. In United States Military guise, the weapon will be known as the Remington ACR as it is to be distributed through the Freedom Group's Remington branch.
The ACR is the primary weapon of Task Force 141 and also used by General Shepherd's Shadow Company in single player. In multiplayer the ACR is unlocked at level 48, it has a significantly low damage output compared to other assault rifles making it one of the weaker if not weakest in the normal game types. Having virtually no recoil even when fired at full auto however makes it the best assault rifle to effectively use the ACOG scope attachment and maintain accuracy at long distances.