at the Springfield Armory in May 1917. In the first test, the weapon fired 20,000 rounds with only a few malfunctions mostly related to poorly loaded cloth belts. 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. The Ordnance Board was impressed, but was unconvinced that the same level of performance could be achieved in a production model. Consequently, Browning used a second gun that not only duplicated the original trial, but it also fired continuously for 48 minutes and 12 seconds (over 21,000 rounds). The Army adopted the weapon as its principal heavy machine gun, utilizing the M1906 .30-06 cartridge with a 150-grain, flat-base bullet. Unfortunately, production was a problem. Several manufacturers started producing the gun, but they had to set up the assembly lines and tooling. By 30 June 1918, Westinghouse had made only 2,500 and Remington had made only 1,600. By the time of the Armistice, Westinghouse had made 30,150, Remington 12,000, and Colt 600. Until the start of World War I, the Army had used a variety of older machine guns, like the M1895 Colt–Browning machine gun "Potato Digger" (which Browning had also designed) and weapons like the Maxim Gun, the Benet–Mercie M1909, and the Hotchkiss M1914 machine gun. Although the Model 1917 was intended to be the principal US Army heavy machine gun in the war, the Army was, in fact, forced to purchase many foreign weapons—the French-produced Hotchkiss 8 mm machine gun was actually the most common heavy machine gun used by the American Expeditionary Force. In 1926, the Browning's rear sight was revised to incorporate scales for both the new M1 Ball (172-grain boat-tail bullet) and the M1906 (150-grain flat-base bullet) ammunition. With M1 ball, the M1917 had a maximum range of about ; with M2 ammunition, about . The rear sight had a battle sight as well as a raised leaf-type sight suitable for employment against either ground or air targets. Service The M1917 saw limited service in the later days of World War I. Because of production delays, only about 1,200 Model 1917s saw combat in the conflict, and then only in the last 2½ months of the war. Some arrived too late for combat service. For example, the 6th Machine Gun Battalion, fighting as part of the Second Division did not exchange their Hotchkiss M1914 machine