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I have wanted to do an M37 Web site for some time, but without an actual M37 to photograph, getting the images I needed had proved impossible. At last the elusive M37 has become available to the collectors community through the efforts of a fellow collector, Joe Hanaish. Special thanks go to Joe, as well as James Malarkey of Allied Armament for their generous loan of the M37 photographed for this site. There are few images of the M37 to be found in either books or Web sites, and without this crucial help this site would not have been possible. I ended up purchasing the M37. After firing and photographing it I had become so impressed with this "ultimate" 1919 that I could not bear to part with it. While Allied Armament is no longer in business, I have left the Allied page up because it contains information you may find useful. You will also find there some background information on how Joe Hanaish was able to accomplish this remarkable feat.
The M37 was the cream of the ground .30 caliber air-cooled Brownings. It was also, sad to say, the last production .30 caliber Browning to be adopted by the US military. 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 (shown below, right) and the T-153 .

T-152 tank gun. Source: Small Arms of the World, 9th Edition, by W.H.B.Smith.
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.*
*From The Browning Machine Gun, by Dolf Goldsmith

RSP engraving on the M37C at left.
Photo courtesy of
At left is a Saco-Lowell M37 fixed weapon. The difference between the flexible M37 and fixed M37C appears to be the absence of a rear sight on the fixed version. This example has an altered retracting slide.
Photo courtesy of
Principal Differences Between the 1919A4 and the M37

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 Source: ( It also saw service in Viet Nam on the HU-1 Huey as a skid mounted fixed weapon.

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M37Cs in an armory in Viet Nam. Eight rows are visible in the photo, with 60 guns to a row = 480. Note the missing rear sights. The M60 was adopted in 1957, yet the M37 remained in service for tank and helicopter use into the late 1960s. The M37 was the better weapon, and I'm sure the armorers in Viet Nam knew this. On the left are Browning .50 caliber HBs.
Photo courtesy of

M48 Patton

M60 Patton
Source: Source:

Cradle for Patton tank secondary armament role.

H-23D Raven armed with twin M37C .30 Cal. machine guns
on XM1 armament subsystem.

Loading linked 30-06 ammunition on a skid mounted M37 on an UH-1 Huey. The ammunition is fed through the floor. Note large chute for deflecting brass and the long lever attached to the retracting slide.

M37 subsystem for helicopter skid mount.

Graphic and photo above are courtesy of