30 mm caliber ammunition is usually used in autocannon. Such ammunition includes NATO standard 30×173 mm and 30×113 mm B rounds and Soviet 30×165 mm rounds widely used around the world.

30 mm ammunition is typically not used against personnel, but rather as an anti-materiel or armor-piercing round. Rounds of this size can be effective against armored vehicles as well as fortified bunkers.

The Armed Forces of the Russian Federation use their 30 mm weapons in a variety of vehicles, including the Su-25 attack aircraft, Mi-24 helicopter, Mi-28 attack helicopter, Ka-50 attack helicopter, and the BMP-2, BMP-3, and BTR-90 infantry fighting vehicles. The most modern anti-aircraft gun systems in use by Russia are in 30mm. The U.S. military uses 30 mm weapons in their A-10 Thunderbolt II and AH-64 Apache helicopter. It was going to be used in the Expeditionary Fighting Vehicle until the project was cancelled.

30 mm ammunition generally comes in three varieties: armor piercing (AP), high explosive (HE), and training rounds. Armor piercing and high explosive cartridges usually also possess incendiary characteristics.