assault gun

An assault gun is a gun or howitzer mounted on a motor vehicle or armored chassis, designed for use in the direct fire role in support of infantry when attacking other infantry or fortified positions.Historically the custom-built fully armored assault guns usually mounted the gun or howitzer in a fully enclosed casemate on a tank chassis. The use of a casemate instead of a gun turret limited these weapons' field of fire, but provided a simpler construction that was cheaper to build and less prone to mechanical breakdowns. The increased space and reduced weight of the turretless design also allowed mounting a larger weapon and providing heavier frontal armour on any given chassis, and in most cases these turretless vehicles also presented a lower profile as a target for the enemy.
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Noun
1. any of the automatic rifles or semiautomatic rifles with large magazines designed for military use
(synonym) assault rifle
(hypernym) automatic rifle, automatic, machine rifle
(classification) military, armed forces, armed services, military machine, war machine
2. an armored vehicle with the chassis of a tank (but no turret) and a large gun; used as an antitank weapon and to support infantry
(hypernym) armored vehicle, armoured vehicle