The reliability was exceptional, so Browning fired another 20,000 rounds through the weapon with one broken part: a broken sear at about 39,500. : 176 In the first test, the weapon fired 20,000 rounds with only a few malfunctions mostly related to poorly loaded cloth belts. Browning arranged a test at the Springfield Armory in May 1917. : 173–174 The government asked several designers to submit weapons. arsenal included only 1,100 machine guns, and most of those were outmoded. The Army Ordnance Department showed little interest in machine guns until war was declared in April 1917. The belt fed left-to-right, and the cartridges were stacked closer together than Maxim/Vickers (patterns copied by most guns later). Its sliding-block locking mechanism saved weight and complexity, and was used in many previous Browning designs. The only similarities with the Maxim or Vickers are the principles of recoil operation, T-slot breechblock, "pull-out" belt feed, water cooling, and forward ejection. At 47 pounds (21 kg), it was much lighter than contemporary Maxim type guns such as the first 137-pound (62 kg) German Maschinengewehr 08 (08/15 model: 43 lb (20 kg) and the British Vickers machine gun, while still being highly reliable. Unlike many other early machine guns, the M1917 had nothing to do with Maxim's toggle lock design.
The Browning is a water-cooled heavy machine gun, though some experimental versions were made that did not use a water jacket the air-cooled M1919 was later developed as a medium machine gun. Val Browning, the inventor's son, demonstrates the M1917. The M1917A1 had a cyclic rate of 450 to 600 rounds per minute. The M1917, which was used on some aircraft as well as in a ground role, had a cyclic rate of 450 rounds per minute. There were two main iterations: the M1917, which was used in World War I and the M1917A1, which was used thereafter. It was used at the battalion level, and often mounted on vehicles (such as a jeep). It was a crew-served, belt-fed, water-cooled machine gun that served alongside the much lighter air-cooled Browning M1919. The M1917 Browning machine gun is a heavy machine gun used by the United States armed forces in World War I, World War II, the Korean War, and the Vietnam War it has also been used by other nations.