Rock Island Arsenal M37

The M37 .30 caliber machine gun is an automatic, recoil-operated, link-belt fed, air-cooled weapon. The gun is designed for fixed or flexible use. After WW2 the Army needed an improved tank machine gun. The 1919A4 had some drawbacks as a coaxial tank MG so work began around 1950 to produce a serviceable weapon. Design prototypes included the 1919A4E1, T-151, T152 and the T-153. The T-153 was ultimately adopted as the M37 in 1955 and the contract for production was awarded to the Saco-Lowell Shops. Rock Island Arsenal was another manufacturer of the M37 and produced 7,340 guns from 1955 to 1957. The M37 can be fed from either side and has a link chute opposite the feed side. The bolt has dual tracks for alternate operation of the belt feeding pawl. The pawl can be reversed and the pawl lever moved to the other side. Two wedge shaped switches close off the unused track, and the ejector can be reversed. The top cover can easily be opened from either side by rotating a winged knob. The gun is charged from the rear via a retracting slide. The driving spring is captive and is secured to the right side plate at the rear by sliding a conical block into a dovetailed slot. There is no driving spring rod protruding through the back plate. The back plate envelopes the receiver sides and can be easily removed by depressing a latch at the top. There is a horizontal trigger safety, and the left side sight base has been eliminated. The rear sight base is integral to the top plate. The M37 was primarily a tank gun and was used on both the M48 & M60 Patton medium tanks. The fixed version, the M37C was also used on the OH-13 Sioux and OH-23 Raven helicopter gunships on the skid-mounted M1 armament subsystem.