The Model of 1917 Browning Water-Cooled Machine Gun
By Robert G. Segel

Not long after John Browning invented the world’s first gas operated fully automatic machine gun, the Model 1895 Automatic Gun, he realized that there must be a better, simpler, more efficient operating system. He set about to create his version of a short-recoil operated machine gun that was significantly different from the then current Maxim design.

The Model 1901

On June 19, 1900, Browning was granted U.S. Patent No. 678,937, which was his first patent on a recoil operated machine gun. This “first” gun was substantially different from his later, more familiar, versions. The gun ejected the empty brass cartridges out to the right side rather than through the bottom, had an external feed lever, a specialized cartridge belt that left most of the cartridge body exposed, and its trigger and firing mechanism were significantly different and featured a hammer driven firing system. Nevertheless, this first model set the stage for further development and had many features that are recognizable in his later guns. This included a barrel attached to a separate barrel extension, an accelerator to speed up the movement of the bolt, a rising breech block, a claw extractor and a recoil spring guide with a coil recoil spring that could be turned thus locking the recoil spring inside the bolt body.

The tripod cradle he created in his workshop for this gun was reminiscent of the type and style as used on the Model 1895 Automatic Gun and used the Model 1895-style belt box with a sliding lid.

Browning informed the U.S. Ordnance Department of his new invention, but they were not interested and it appears that they never even examined it for testing.

The Model 1910

Over the next several years, Browning continued to work to refine his recoil operated machine gun. He redesigned much of the internal operating system eliminating the hammer method of firing and replaced it with a firing pin with a sear notch on the end and added a trigger bar that engaged a sear that released the sear notch on the firing pin. He added a pistol grip with fiber buffer discs that absorbed excess energy and helped “bounce” the bolt back to battery and simplified the ejection system to eject the spent cartridges out through the bottom. There were other minor improvements as well such as using breech lock depressors to help disengage the breech lock from the locking recess in the bottom of the bolt. It was this gun, the Model 1910, that was the basis of the M1917. Browning also redesigned the cradle for the gun to sit in that became the M1917 tripod. (For a detailed description of the M1917 tripod, see Small Arms Review, Vol. 10, No. 4, January 2007.)

All of the refinements that were incorporated in the Model 1910 were done on Browning’s own initiative. His business was thriving with hunting and sporting weapons and there was no governmental interest in his machine gun, yet he was determined to produce an efficient weapon that required very little adjustment, could produce a high volume of fire and be operated by a soldier with minimal training, with simplicity of construction that enabled cost effective manufacturing. Since there was no market for his new machine gun, he decided to just “sit on it” until an appropriate time that his new invention was needed. However, Browning continued to work on his new invention and on October 13, 1916 applied for another U.S. patent based upon his perfected recoil-operated machine gun; the Model of 1910 that ultimately became the Model of 1917. It is interesting to note that by the end of 1916, it had become apparent that the United States would be drawn into the war in Europe and so patent applications on war materiel were withheld as once a patent was granted it became public knowledge and thus available to everyone - including our enemies. The patent was eventually granted three months after the war ended on February 4, 1919 as U.S. Patent No. 1,293,021: Automatic Machine Gun.

The U.S. government showed practically no interest in machine guns. It had adopted the Maxim gun in 1904 and the Benet-Mercie machine rifle in 1909, but both weapons were few in numbers and tactics were sorely lacking. When war broke out in Europe in 1914, there was again a slight flurry of machine gun interest in the U.S. and the Vickers was adopted in 1915. But even with almost three years to prepare for the eventual U.S. involvement in World War I in 1917, there was no effective machine gun development program despite of the fact that it was obvious that the war in Europe was a machine gun war. It was under such circumstance that the American Expeditionary Force that went to France in 1917 went to war with no machine guns and had to be initially equipped with the French M1914 Hotchkiss heavy machine gun and the disastrous M1915 Chauchat machine rifle.

In 1917, after much delay, procrastination and indecision, the U.S. finally put out a call to American inventors to submit designs for consideration. John Browning had been waiting for just such a call and personally traveled to Washington, D.C. to present his guns. That is guns, plural, because besides bringing his improved Model of 1910 water-cooled machine gun, he also brought along another project he had been working on: the Browning Automatic Rifle (BAR).

In May, 1917 the official endurance trial test was held at the Government Proving Ground at Springfield Armory. The Army requested that 20,000 rounds be fired. The 20,000 rounds were fired without a malfunction or broken part. And, to the amazement of all, Browning fired an additional 20,000 rounds - 40,000 rounds in total - with just one failure of a component part. The board overseeing the test consisted of five Army officers and two civilians appointed by the Secretary of War and they recommended the immediate adoption of the weapon as the Model of 1917 noting the outstanding reliability and simplicity of design. They were particularly impressed that the officers who demonstrated the gun were able to take the gun apart and put it back together in minutes - blindfolded. This had never been done before and became the standard “blindfold test” at machine gun schools.

Browning knew that there still needed to be some refinements done on the heavy machine gun. He returned to the Colt factory, who had exclusive manufacturing rights, to personally improve and function test the gun to make certain it was ready for a public demonstration at Congress Heights just outside Washington D.C. on February 27, 1918. Two Model 1917s were fired before a crowd of three hundred dignitaries and guests that included the military, politicians, foreign observers and the press. Both guns performed excellently and were well received. The press was particularly enamored with the highly successful demonstration and many newspaper articles appeared around the country extolling the virtues of Browning’s new gun.

Model of 1917

It soon became evident that no one single manufacturer could produce the vast quantities needed. Colt had an agreement with Browning to produce guns of his design exclusively but there was no way they could do it alone as the Colt manufacturing facilities were already at full capacity with other production. Colt made the rights available to the government and in July, 1917 delivered gages and drawings that other companies would use to produce the guns.

Colt established a manufacturing facility in Meriden, Connecticut to produce 10,000 guns. In September of 1917, Remington Arms Company of Illion, New York was given a contract to manufacture 15,000 guns. And on January 10, 1918, New England Westinghouse was given a contract to produce 20,000 guns.

Because of Colt already being in production of other weapons, most notably the Vickers Model of 1915, and the time required to start up the new facility in Meriden, Colt was the last of the three manufacturers to get up to speed in late June, 1918 with the production the M1917 Browning, producing only 600 guns by the time of the Armistice in November, 1918. Remington also experienced delays due to completing a Russian contract and didn’t begin production until May, 1918. By the end of the war Remington had produced 12,000 guns. It was, however, Westinghouse, that stepped in with an outstanding production schedule. Within 29 days of receiving the contract on January 10, 1918, Westinghouse had produced a hand-made prototype production gun and, 63 days later, the first production gun came off the manufacturing line. Just nine months later when the Armistice was signed on November 11, 1918, Westing-house had manufactured 30,150 guns and was producing guns at the rate of 500 per day. As was so often the case in the past, and still is currently, the U.S. was ill prepared for war and the industrial might of the U.S stepped up to meet the demand.

Into The Crucible - Finally

A machine gun training facility was established at Camp Hancock in Augusta, Georgia though the majority of the graduates never engaged in combat in France. The first Browning guns arrived in France on June 29, 1918 and shortly thereafter, training commenced there even though there was a shortage of guns, spare parts and instructors. The shortage of instructors was so acute that Val Browning, John Browning’s son, went to France to be an instructor on the new gun. As more guns arrived and the training continued, particularly with the 79th and 80th Divisions, the guns were ready to be fielded for combat in September of 1918. The first instance of combat usage was in the Meuse-Argonne Forest on September 26, by a small detachment of the 79th Division, where in the wet and muddy conditions, the new Browning performed exceptionally well with one company firing 10,000 rounds per gun.

In all, a total of 1,168 Browning guns actually made it to the front lines of World War I seeing action for only two months before the war ended. While that number may initially seem impressive, it was not, as only a very small portion of the Allied Expeditionary Force was so equipped. It was too little, too late. But that didn’t matter because the fresh influx of American troops fighting against an army that, after fours years of decimating casualties, was the final hammer blow to a substantially weakened enemy. Nevertheless, it should be noted that even in the German Army’s death throes in those final three months, they fought valiantly to the end and inflicted serious casualties on the American fighting forces who were generally equipped with French machine guns and the U.S. Model of 1915 Vickers, not the new Brownings. And, there were problems with the new gun.


Because the gun was accepted so quickly, a full trial of tests of all aspects of the gun were either omitted or rushed so as to get the gun into production. Further testing was conducted while the gun was in production but production guns were entering the field with flaws. It was probably fortunate that the gun actually saw limited combat use. If it had been used longer under the harsh and demanding conditions that permeated WWI, the failure rate would have mounted very quickly. Though there were few problems encountered regarding the functioning of the guns in the field, there were a high number of parts failures due to improper material preparation, poor workmanship and inspection.

The list of parts failure was extensive, and included accelerators, ejector pins, worn out barrels (that had a life of only about 8,000 rounds), extractors, barrel extensions, extractor cam plungers, firing pins, belt holding pawl springs, sears, etc. The list continued naming another twenty key components. Many of the parts problems were due to improper heat treating and poor workmanship. The two most serious defects were leaking water jackets both at the end cap and at the trunnion block due to improper manufacturing techniques at Westinghouse and, the biggest problem, was cracked bottom and side plates due to a flaw in the design of the support of the breech lock cam, which produced a lot of stress on the bottom and side plates. Even as guns were being manufactured, shipped and fielded, testing continued back at Westinghouse, Remington and Colt to try and work out problems. This included a number of interchangeability tests to assure parts from one manufacturer would fit in the gun of another manufacturer.

Post War WWI Development

It was fortunate that the war ended when it did in terms of working out the problems on the M1917 Browning water-cooled machine gun. Production continued after the war with most of the 72,500 guns ultimately produced being assembled in the post war era. It was during this time, from about 1919 to the mid 1930s that work continued to perfect the Browning. Comprehensive testing continued, metallurgy improved, standardization of manufacturing processes was established and different design changes were conceived and tried. In 1922, the rear sight was changed from meters to yards. (Meters were used as all the firing tables and maps used in World War I were in meters.) In 1925, there were modifications to the buffer to accommodate the 15% increase in recoil energy due to the adoption of the more powerful 172-grain boattail M1 .30-06 cartridge, but the sight graduation wasn’t changed until 1932.

The biggest modification was the retrofitting of M1917s with a reinforcement stirrup under the breech lock cam to strengthen the sides and bottom plate. Different methods were used as were different sizes of brackets. Initially, a simple “U” bracket was either riveted or welded just under the breech lock cam. It wasn’t until 1936 that a program was initiated by Rock Island Arsenal to convert all existing Model of 1917 Brownings with all the upgrades. Some of the changes included a large, new-manufactured reinforced bottom plate that extended up the sides of the receiver and riveted in place, a new belt feed lever and the new rear sight in yards for the M1 ball cartridge. A new tripod cradle was also introduced that simplified construction and incorporated a traverse and elevation mechanism as one unit at the rear of the cradle. This improved version of the Model of 1917 was designated as the M1917A1. (The “Model of” designation for U.S. arms was dropped in 1939 and replaced with the letter “M”.)


During World War II, more changes occurred to the M1917A1 that included an improved bolt, the bronze end cap and trunnion block replaced by steel, the steam tube assembly was strengthened and the rear leaf sight graduated for the now standard M2 ball cartridge. While almost all Model of 1917s were ultimately converted to the A1 specifications, production resumed from 1936 to 1945 with 55,869 M1917A1s being produced by Rock Island Arsenal.

The M1917A1 was the final achievement of the heavy water-cooled machine gun. The water-cooled Browning was already considered obsolete by the end of World War II because of its use of water and weight and was ultimately supplemented with the light weight air-cooled Browning M1919A4, which functioned exactly the same as the M1917A1, and used the same internal parts, except without the water jacket and used a light weight M2 tripod. Nevertheless, the M1917A1 was used extensively in both theaters of operation during World War II and continued service throughout Korea and the beginning stages of the Vietnam War.

John Browning’s vision of a simple and reliable machine gun operating system is a testament to his inventive genius. The exact same operating principle was applied to the larger .50 Browning M2 machine gun that is still in use to this day.


Accessories for the M1917 consisted of a water condensing can, water condensing hose, flash hider, combination tool, M1917 clinometer, M1918 belt filling machine, headspace and timing gage and a ruptured case extractor. Ammo boxes were made of wood in two styles, both slotted to fit on the M1917 cradle. The two styles of wood boxes differ in that the early ones had a straight front while the later ones had a slanted bottom to the front. This was so they would also fit on the short lived M1918 tripod cradle.

Accessories for the M1917A1 consisted of those accessories mentioned above, albeit with some updating and modifications, as well as several styles of metal ammunition cans, carrying handle, anti-aircraft front sight, anti-aircraft tripod extension, and canvas covers of various types.

Field Stripping the Model of 1917 by Assemblies.
  • Make sure the gun is unloaded by checking to make sure there is no belt in the feedway. Open the top cover and cycle the bolt to the rear three times and visually check the chamber and T-slot on the bolt face that no cartridges are present. Return bolt to forward position and close top cover.
  • Drain water from the water jacket by unscrewing the water jacket drain plug.
  • Pull the bolt handle back and hold in that position.
  • Push in on the driving spring rod protruding from the rear of the back plate and turn to the right so that the lugs on it will catch in undercut recesses in the bolt. Use a screwdriver or the base (rim) of a cartridge to turn the driving spring rod.
  • Push the bolt handle forward so as to remove the driving spring rod from the hole in the back plate.
  • Pull back on the top cover latch and open the top cover. Then, push the top cover latch forward and lift out the back plate.
  • Pull the bolt handle all the way back and draw the bolt handle out to the right.
  • The rear of the bolt will be visible. Grasp it by the top and bottom with the thumb and forefinger and pull it out of the rear end of the receiver. In order to get a better grip on the bolt, it can be pushed backwards from inside the receiver. Make certain that the driving spring rod is not pointed at the hand or any other part of the body or another person. It must be pointed in a safe direction. The driving spring rod is under tremendous spring tension, and if it should become loose (which can happen) it will be a very dangerous missile.
  • Push in on the trigger pin through the hole located on the right side of the receiver with the point of a bullet. Take hold of the trigger and draw the entire lock frame, barrel extension and barrel unit all the way out to the rear.
  • Holding the barrel tightly, take hold of the lock frame and hold securely while pushing forward on the accelerator with the thumb. This unlocks the lock frame and barrel extension, which allows them to be separated.
  • Unscrew the barrel from the barrel extension.
  • Each complete assembly is now separated from any other assembly.
  • To reassemble the weapon, reverse the order.

This article first appeared in Small Arms Review V10N5 (February 2007)
and was posted online on December 14, 2012


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