field gun;  field artillery
 main battery;  main armament
 empty gun;  gun loaded with blanks;  firing a blank
 anti-aircraft gun;  antiaircraft artillery
 cannon (esp. high-velocity artillery)
 gunport;  embrasure;  muzzle
 rapid-fire gun or cannon;  talking rapidly;  barrage of words or questions
 secondary armament (of a warship);  secondary battery;  secondary gun
 cannonball;  shot (in the shot put)
 railgun;  firearm that uses electromagnetism to propel a projectile
 battery (of artillery, cameras, etc.);  barrage
 mounting for two or more guns (e.g. naval turret, tank)
 cannon (esp. high-velocity artillery)
 cannon (esp. high-velocity artillery)
 recoilless rifle;  recoilless gun
 high-angle or anti-aircraft gun
 single-mounted gun (naval turret, tank, etc.)
 air defense artillery;  air defence artillery
 cannon containing a recoil system