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The 20 mm caliber is a specific size of cannon or autocannon ammunition. There are few weapons (aside from shotguns and large game hunting rifles) which have been built that fire projectiles between .50 caliber (, roughly 13 mm caliber) and 20 mm caliber, though the 14.5 mm caliber is used by some Soviet machineguns such as the KPV and anti-tank rifles such as PTRS, PTRD, and NTW-20. A very small number of anti-tank rifles have been produced in 20 mm and larger calibers. 20 mm caliber cartridges have an outside bullet diameter and inside barrel diameter of . Projectiles or bullets are typically long. Cartridge cases are typically long. Many but not all 20 mm rounds have an explosive filling and detonating fuze. As an example, the 20×102mm has a 100-gram bullet fired at a muzzle velocity of . For a simple slug round this is a muzzle energy of . ==Usage== Like most cannon ammunition, 20 mm caliber weapons are typically used against large targets such as vehicles, buildings, or aircraft. Though lethal against individual soldiers, 20 mm ammunition is so large and heavy that its effects are inefficiently utilized on such relatively small targets. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「20 mm caliber」の詳細全文を読む スポンサード リンク
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