A Gauss rifle, better known as coilgun, is a special type of electromagnetic accelerator that is capable of accelerating a metal bullet by exploiting the electromagnetic forces created in the barrel by means of special windings.

Unlike conventional firearms, the thrust given to the projectile is not provided by the combustion of explosive mixtures (eg. gunpowder) but by the electromagnetic forces that arise when a ferromagnetic object (the projectile) is subjected to a magnetic field.

The invention of these accelerators is due to the Norwegian scientist Kristian Birkeland who developed the first model of electromagnetic cannon in 1904. The name Gauss rifle refers to the mathematician Carl Friederich Gauss who formulated the electromagnetic laws that govern the phisic fenomena behind the functioning of the weapon.

Coilguns should not be confused with railguns, which are another type of electromagnetic accelerator that uses magnetic induction in a completely different way.