The XM806 was initially developed as a "lightweight" heavy-class, belt-fed machine gun for the United States Army as possible replacement for the legendary Browning M2 heavy machine gun line. The program was headed by General Dynamics and given the long-form designation of "Lightweight .50 Caliber Machine Gun" (LW50MG). The new weapon followed the abandoned XM312 which, itself, was intended as a replacement for the venerable Browning M2. The XM806 was developed along these same lines before the program was cancelled in full in July of 2012.
The XM806 weighed some 40lbs sans its tripod assembly and featured a recoil-operated, belt-fed (m9 belts) action chambered for the .50 BMG cartridge. Its rate-of-fire was 265 rounds-per-minute and the weapon could achieve a sustained rate of 40 rounds-per-minute if pressed. A specially-designed M145 optic system was supported though iron sights were standard. The optics could be fitted across a span of Picatinny rail seated over the receiver. The charging handle was set to the right side of the rectangular receiver with a barrel change handle along the left. Barrel-changing was a requirement of such air-cooled weapons, lest they fracture or deform due to the generated heat of each successive shot. The muzzle was capped by a conical flash suppressor and actuation of the weapon was through traditional spade-type grips at the rear.
While the XM806 was evolving into a promising battlefield system, it program delays and ultimate disinterest led to its cancellation. In turn, the US Army furthered the M2A1 mark for the Browning M2 line which brought about use of a Quick-Change Barrel (QCB), reduced muzzle flash and other refinements over the original, long-running weapon. It was expected that some 45,000 M2s were to be "modernized" to the new M2A1 standard.