30 mm caliber

The 30 mm caliber is a specific size of autocannon ammunition. Such ammunition includes NATO standard 30×113mmB, 30×173mm (STANAG 4624), and 35x228mm NATO rounds, Soviet 30×165mm, 30x210mmB, and 37×250mm, Yugoslav 30x192mm, and Czechoslovak 30x210mmCz rounds which are widely used around the world.
Usage.
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 lightly armored vehicles as well as fortified bunkers. 30mm is also a popular calibre for shipboard close-in weapons systems, such as the Russian AK-630 and Dutch Goalkeeper CIWS.
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 30 mm. 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.
Types of 30 mm ammunition.
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.