The prime producer of the M60 has been the Maremount Manufacturing Co of Saco in Maine, and large numbers have been produced to equip all arms of the US forces. Despite the protracted development of the M60 it still has some debatable features - the barrel heats quickly and is not easy to change rapidly, and the carrying handle is fragile and awkward. Also the M60 is rather on the heavy side for use as a squad weapon. Mounted on the M122 tripod, the M60 has limitations on sustained fire. Vehicle mounting is the M4 pedestal mount. Basically, the M60 is gas operated and can fire automatic only from a disintegrating metallic-link belt.. As the first round travels down the barrel, it pushes gas into the gas cylinder through a hole in the bore. The pressure generated in the cylinder then forces a piston down the chamber, moving the bolt back and bringing the next round into place. Once the firing pin hits the bullet and sends it speeding out of the barrel, the cycle is repeated for as long as the trigger is depressed.