Gun arc
The horizontal span a gun can cover without turning the hull, on vehicles that have no rotating turret.
Also known as traverse arc, horizontal arc, casemate arc.
A casemate vehicle mounts its gun in the hull with limited side-to-side travel, quoted as an arc in degrees. Anything outside it requires turning the whole vehicle, which costs time and widens dispersion.
A narrow arc is the defining weakness of most tank destroyers: they are lethal down one line and defenceless against anything that gets beside them.
Related terms
TurretThe rotating housing for the gun, whose armor and traverse speed decide how a vehicle fights from cover.Tank destroyerThe ambush class: high penetration and damage from a fixed or limited arc, usually with strong concealment and thin sides.BloomThe widening of the aiming circle caused by moving, traversing or firing, and the reason a gun's paper accuracy is rarely what a player experiences.