The M60 machine gun (fig. 3-68) is an air-cooled, belt-fed, gas-operated automatic weapon. The machine gun was originally developed for use by ground troops; however, it is used on many types and classes of ships, river patrol craft, and combat helicopters.

The essential features of the M60 are as follows:

The M60 has a front sight permanently affixed to the barrel. The rear sight leaf is mounted on a spring type of dovetail base (fig. 3-69). It can be folded forward to the horizontal when the gun is to be moved. The range plate on the sight leaf is marked for each 100 meters, from 300 meters to the maximum effective range of 1,100 meters. Range changes maybe made by using either the slide release or the elevating knob. The slide release is used for making major changes in elevation. The elevating knob is used for fine adjustments, such as during zeroing. Four clicks on the elevating knob equal a 1-mil change of elevation. The sight is adjustable for windage 5 mils right and left of zero. The windage knob is located on the left side of the sight. One click on the windage knob equals a 1-mil change of deflection.

Figure 3-68.-M60 machine gun: (A) Bipod mounted; (B) Tripod mounted.

NOTE

1 mil equals 1 inch at 1,000 inches, 1 yard at 1,000 yards, 1 meter at 1,000 meters, and so on.

A safety lever is located on the left side of the trigger housing. It has an S (SAFE) position and an F (FIRE) position. On the SAFE position the bolt cannot be

Figure 3-69.-M60 rear sight.

pulled to the rear or released to go forward. The cocking lever, on the right side of the gun, is used to pull the bolt to the rear. It must be returned manually to its FORWARD position each time the bolt is manually pulled to the rear.

The M60 machine gun may be installed in helicopters by use of special mounts installed in the doors or escape hatches. The mount consists of an ammunition can support, a spent round chute, a link chute, and a stowage bag. The machine gun can be easily installed and removed from the mount by use of quick-release pins. Firing stops are incorporated into the design of the mount to determine the azimuth and elevation limits of the machine gun.