known as the CS/LM6, which was released publicly in 2010 in foreign weapons expo conventions. It was made with a picatinny rail on the receiver in order to have quick installation of various optics. The original M2HB tripod and parts can be used on the CS/LM6. M2A1 When the M2 was first being designed, John Browning faced two design challenges. With the machine tools available at that time, the dimensions that established the location of the bolt face and the depth of the chamber could not be held tightly enough to control the fit of the cartridge in the chamber. The round can be too tight in the chamber and the gun would not fire, or be too loose in the chamber, resulting in a stoppage or ruptured cartridge. The other dimension that could not be held closely enough was when the firing pin would fall. The solution to these problems was adjustable timing and headspace ("Timing" is the adjustment of the gun so that firing takes place when the recoiling parts are in the correct position for firing; "headspace" is the distance between the face of the bolt and the base of the cartridge case, fully seated in the chamber); the operator had to screw the barrel into the barrel extension, moving the barrel toward the bolt face to reach the proper headspace with simple gauges to allow the operator to adjust to the proper dimensions. By the late 20th century, the M2 was the only adjustable headspace weapon in the U.S. inventory. With rising reports of injuries from improperly headspaced weapons, the U.S. military held a competition for a quick change barrel conversion kit with fixed timing and headspace in 1997. Three companies offered kits and Saco Defense won the competition. However, funding was lost before the design could be fully evaluated and the program ended. In 2007, the military found money to start a new competition. Saco Defense had since been acquired by General Dynamics, which won the competition. On October 15, 2010, the M2A1 heavy machine gun was type classified by the U.S. Army. Formerly known as the M2E2, the M2A1 incorporates improvements to the design including a quick change barrel (QCB) with a removable carrying handle, a new slotted flash suppressor that reduces muzzle flash by 95 percent, fixed headspace and timing, a modified bolt, and a manual trigger block safety. When a standard M2