Crew-served weapon in the context of "Fire-control system"

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.

A shootout, also called a firefight, gunfight, or gun battle, is a confrontation in which parties armed with firearms exchange gunfire. The term can be used to describe any such fight, though it is typically used in a non-military context or to describe combat situations primarily using firearms (generally excluding crew-served weapons, combat vehicles, armed aircraft, or explosives).

Shootouts often pit law enforcement against criminals, though they can also involve parties outside of law enforcement, such as rival gangs, militias, or individuals. Military combat situations are rarely titled "shootouts", and are almost always considered battles, engagements, skirmishes, exchanges, or firefights.

An improvised fighting vehicle is an ad hoc combat vehicle resulting from modified or upgraded civilian or military non-combat vehicle, often constructed and employed by civilian insurgents, terrorists, rebels, mobsters, guerrillas, partisans, drug cartels, criminal organizations or other forms of non-state militias and irregular armies. Such modifications usually consist of grafting improvised armour plating and fixed crew-served weapons such as heavy machine guns or antiaircraft autocannons mounted onto the back of a utility vehicle or pickup truck.

Various militias and official militaries have improvised such vehicles ever since the introduction of the first automobiles into military service. During the 1910s and 1920s, the absence of a doctrine for the military use of automobiles or of an industry dedicated to producing them led to a great deal of improvisation in the creation of early armored cars and similar vehicles.

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:

An anti-materiel rifle (AMR) is a rifle designed for use against military equipment, structures, and other hardware (materiel) targets. Anti-materiel rifles are chambered in significantly larger calibers than conventional rifles and are employed to eliminate equipment such as engines and unarmored or lightly armored targets. Although not originally designed for use against human targets, the bullet mass and velocity of anti-materiel rifles gives them exceptional long-range capability even when compared with designated sniper rifles. Anti-materiel rifles are made in both bolt-action and semi-automatic designs.

The anti-materiel rifle originated in the anti-tank rifle, which itself originated during World War I. While modern tanks and most other armored vehicles are too well protected to be affected by anti-materiel rifles, the guns are still effective for attacking unarmored or lightly armored vehicles. They can also be used against stationary enemy aircraft, missile launchers, radar equipment, unexploded ordnance, small watercraft, communications equipment, crew-served weapons and similar targets. Their value lies in their ability to precisely target and disable enemy assets from long range at relatively low cost.