John Browning's heavy machine gun, the longest-serving American crew-served weapon still in active military use. The M2HB has been in continuous service since 1933 and remains the standard heavy machine gun of the US military and dozens of allied nations. Type: Rifle Action: Full-Auto Caliber: .50 BMG Year introduced: 1933, USA Weight: 84 oz Overall length: 65" Status: Active Military use: Yes Intended use: Military, Collecting, NFA