A Rail Gun is the primary armament of the United Nations Navy and Martian Congressional Republic Navy it is also called a Gauss Turret. The Donnager had rail guns at the beginning of the Series. It is unknown if other UNN or MCRN Cruisers, Frigates, etc. have rail guns excluding the Rocinante.
- Coilguns, which use a sequence of electromagnets to pull a projectile down a barrel can not fire tungsten slugs. If magnetism is used to accelerate its projectiles it would do a poor job in the case of tungsten because it does not possess strong magnetic properties. In the parlance of material science, it is paramagnetic, it is weakly attracted to a magnetic field.
- A railgun uses the Lorentz Force, as in it will move perpendicularly or at a right angle with respect to the direction of the current path and magnetic field, to accelerate projectiles. The effect is initiated when a pair of electrically charged rails is bridged with an electroconductive material, like Tungsten for example .
- Technically in both cases though you can use projectiles that don't fit the criteria of either weapons system, if you use a hybrid design model that incorporates the best of both weapons: A railgun with a non-conductive projectile and a conductive layer at the base; Coil guns that uses a projectile composed of a core or sabot of paramagnetic material wrapped in non-paramagnetic cladding.
- Current US Navy testing of Railguns employ Tungsten projectiles. Should the weapons be deployed, they will use Tungsten or Depleted Uranium projectiles.