Field of fire

The field of fire (also zone of fire, ZF^[1]) of a weapon (or group of weapons) is the area around it that can easily and effectively be reached by gunfire from a given position.^[2]

A similar term sector of fire is used to describe the area into which each gunner or group are allowed to fire. The boundaries are assigned by the commanding officer and thus can be arbitrary, even three-dimensional (a rifleman attacking a building might be assigned a set of windows to target).^[3]

The arc of fire of a mounted gun is a horizontal ("traverse") angle range within which the gun (or guns) can be fired.^[4] It can be limited by the construction of the gun mount or obstacles (for example, superstructure of a ship). If there are no restrictions, the term all-round arc of fire is sometimes used.

The cone of fire describes a cone-like pattern formed by the projectiles with the gun not being moved. It is mostly used in reference to machine guns. The spread of bullets is due to vibration of the gun, tolerances of the ammunition and weapon, and shooter posture. For a typical machine gun, the spread between bullets is proportional to the distance (for example, the width of the cone for M240G is 2⁄1000 of the distance). The cone of fire makes impact in an elliptical pattern called the beaten zone.^[5]

The term originally came from the field of fire in front of forts (and similar defensive positions), cleared so there was no shelter for an approaching enemy.

The beaten zone is a similar concept in indirect infantry small arms fire, specifically machine guns. It describes the area between the "first catch" and the "last graze" of a bullet's trajectory.^{[citation needed]} At the first of these points, a bullet will hit a standing person in the head; at the last of these points, as the bullet drops, it will hit a standing person in the foot. Thus, anyone standing within a given gun's beaten zone will be hit.

Given that there is variance in the path of each bullet, and differences in mechanisms as designed, all machine guns have beaten zones with some width. A good example from history is the duels between Australian soldiers and German MG34 teams, during the 'April battles' and later, at Tobruk during 1941. The much narrower beaten zone of the Mk1 .303 Bren guns helped the Australians to win those duels, despite the Bren's lower rate of fire.

The concept works best as part of a static defense with the area covered by a position plotted out beforehand. Usually the machine guns will be mounted on a tripod and indirect fire sights (such as a dial sight) fitted in addition to, or instead of, direct fire ones. Fire can then be called in by spotters to engage specific points in the guns' field of fire, even if out of sight of the machine gunners.

Overlapping machine guns, creating a crossfire, using the beaten zone concept, together with the idea of enfilading were an important part of World War I.

Beaten zone can also refer to the area that shells will usually land in when fired from an artillery piece. It is in the shape of a rectangle with the longer sides parallel to the direction of fire because artillery tends to deviate more forwards and backwards than right and left.