Coaxial gun

A weapon mount is a weapon component used to affix an armament for stabilization. Weapon mounts can be broken down into two categories: static mounts and non-static mounts.

A static mount is a non-portable weapon support component used on a self-propelled vehicle.

A gun turret protects the crew or mechanism of a weapon and at the same time lets the weapon be aimed and fired in many directions.

A turret is a rotating weapon platform. This can be mounted on a fortified building or structure such as an anti-naval land battery, or on an armoured fighting vehicle, a naval ship, or a military aircraft.

Turrets may be armed with one or more machine guns, , large-calibre guns, missile launchers, and recently directed-energy weapons and Laser Weapon Systems. It may be manned or remotely controlled, and is often armoured. A small turret, or sub-turret on a larger one, is called a cupola. The term cupola also describes rotating turrets that carry no weapons but instead are sighting devices, as in the case of tank commanders. A finial is an extremely small sub-turret or sub-sub-turret mounted on a cupola turret.

The protection provided by the turret may be against battle damage or against the weather, conditions and environment in which the weapon or its crew operate.

A coaxial mount is mounted beside the primary weapon and thus points in the same general direction as the main armament, relying on the turret's ability to traverse in order to change arc. The term coaxial is a misnomer as the arrangement is often actually paraxial (i.e., parallel axes, as opposed to the same axis).

Nearly all main battle tanks and most infantry fighting vehicles have a coaxial machine gun mounted to fire along a parallel axis to the main gun. Coaxial weapons are usually aimed by use of the main gun control. It is usually used to engage infantry or other "soft" targets when the main gun collateral damage would be excessive, or to conserve main gun ammunition.

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Wikipedia