The M2 machine gun or Browning .50 caliber machine gun (informally, "Ma Deuce") is a heavy machine gun that was designed near the end of World War I by
not artillery, where a different definition may apply[citation needed], caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal
Mark 12 5"/38-caliber gun was a United States dual-purpose naval gun, but also installed in single-purpose mounts on a handful of ships. The 38-caliber barrel
The 3-inch/50-caliber gun (spoken "three-inch fifty-caliber") in United States naval gun terminology indicates the gun fired a projectile 3 inches (76 mm)