Weapon mount in the context of "Grenade launcher"

A machine gun (MG) is a fully automatic and rifled firearm designed for sustained direct fire. Automatic firearms of 20 mm (0.79 in) caliber or more are classified as autocannons rather than machine guns.

As a class of military kinetic projectile weapons, machine guns are designed to be mainly used as infantry support weapons and generally used when attached to a bipod or tripod, a fixed mount or a heavy weapons platform for stability against recoil. Many machine guns also use belt feeding and open bolt operation, features not normally found on other infantry firearms.

A weapons platform is generally any structure, vehicle or mechanism on which a weapon can be installed (via various mounting mechanisms) for optimal stability and performance. The mounted weapons, the platform and all other associated supporting equipments together form the weapon system.

In more general use, a weapons platform could be structured around a gun, such as a gun turret on a ship, or bracing on an aircraft. For example, a jet aircraft is a weapons platform for missiles, bombs or autocannons, and the resultant weapon system is the fighter jet; a motorboat can serve as a weapons platform for automatic weapons, torpedoes and flamethrowers, resulting in weapon systems such as gunboats and fast attack crafts. Land vehicles, either wheeled, tracked or mixed, are also considered weapons platforms for grenade launchers, machine guns, recoilless guns and some missile launchers, which transform the vehicles into weapon systems such as armored cars (such as the Humvee), IFVs and technicals (improvised from civilian pickup trucks). In addition, artificial satellites have been proposed as potential space weapon platforms. These satellites could carry an arsenal of weapons, such as to threaten other countries with the possibility of an orbital nuclear strike (see Rods from God).

A gun turret (or simply turret) is a mounting platform from which weapons can be fired that affords protection, visibility and ability to turn and aim. A modern gun turret is generally a rotatable weapon mount that houses the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in some degree of azimuth and elevation (cone of fire).

An autocannon, automatic cannon, machine cannon or anti-tank machine gun, is a fully automatic gun that is capable of rapid-firing large-caliber (20 mm/0.79 in or more) armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bullets) fired by a machine gun. Autocannons have a longer effective range and greater terminal performance than machine guns, due to the use of larger/heavier munitions (most often in the range of 20–60 mm (0.79–2.36 in), but bigger calibers also exist), but are usually smaller than tank guns, howitzers, field guns, or other artillery. When used on its own, the word "autocannon" typically indicates a non-rotary weapon with a single barrel. When multiple rotating barrels are involved, such a weapon is referred to as a "rotary autocannon" or "rotary cannon". If it uses a single barrel with a rotating cylinder with multiple chambers, it is known as a "revolver autocannon" or "revolver cannon"; both of these systems are commonly used as aircraft guns and anti-aircraft guns.

Autocannons are heavy weapons that are unsuitable for use by infantry. Due to the heavy weight and recoil, they are typically installed on fixed mounts, wheeled carriages, ground combat vehicles, aircraft, or watercraft, and are almost always crew-served, or even remote-operated with automatic target recognition/acquisition (e.g. sentry guns and naval CIWS). As such, ammunition is typically fed from a belt system to reduce reloading pauses or for a faster rate of fire, but magazines remain an option. Common types of ammunition, among a wide variety, include HEIAP, HEDP and more specialised armour-piercing (AP) munitions, mainly composite rigid (APCR) and discarding sabot (APDS) rounds.

An altazimuth mount or alt-azimuth mount is a simple two-axis mount for supporting and rotating an instrument about two perpendicular axes – one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth (compass bearing) of the pointing direction of the instrument. Rotation about the horizontal axis varies the altitude angle (angle of elevation) of the pointing direction.

These mounts are used, for example, with telescopes, cameras, radio antennas, heliostat mirrors, solar panels, and guns and similar weapons.

A long gun is a category of firearms with long barrels. In small arms, a long gun or longarm is generally designed to be held by both hands and braced against the shoulder, in contrast to a handgun, which can be fired being held with a single hand. In the context of cannons and mounted firearms, an artillery long gun would be contrasted with a field gun or howitzer.

A general-purpose machine gun (GPMG) is an air-cooled, usually belt-fed machine gun that can be adapted flexibly to various tactical roles for light and medium machine guns. A GPMG typically features a quick-change barrel design calibered for various fully powered cartridges such as the 7.62×51mm NATO, 7.62×54mmR, 7.5×54mm French, 7.5×55mm Swiss and 7.92×57mm Mauser, and be configured for mounting to different stabilizing platforms from bipods and tripods to vehicles, aircraft, boats and fortifications, usually as an infantry support weapon or squad automatic weapon.

A heavy machine gun (HMG) is significantly larger than light, medium or general-purpose machine guns. HMGs are typically too heavy to be man-portable (carried by one person) and require mounting onto a weapons platform to be operably stable or tactically mobile, have more formidable firepower, and generally require a team of personnel for operation and maintenance.

There are two classes of weapons generally defined as HMGs: