Railguns are a different technology from induction guns.
Instead of using a series of electromagnet coils to accelerate a projectile via magnetic induction, a railgun uses very high currents flowing through a pair of parallel rails, with the projectile forming an electrical connection between the two rails.
The magnetic field generated by the current flow pushes on the current flowing through the projectie to accelerate it out of the barrel.
A few weapons of the Verge use railgun technology.
On paper, railguns seem to have many advantages over coilguns.
They are simpler to design and build, making them cheaper and more robust.
They can also deliver higher projectile energies from a given size of gun.
However, they come with numerous drawbacks that discourage their use.
A railgun is less efficient, requiring more input energy for a given kinetic energy imparted into the projectile.
It produces a significant muzzle flash and blast, making it more likely for the shooter to be noticed by enemies and requiring ear protection for recreational shooting.
And most significant, the projectile is in direct mechanical and electrical contact with the rails during acceleration.
This produces rapid wear of the rails, both from mechanical abrasion and erosion by the electrical arc between the rails and the projectile.
Railguns are usually only used in applications where extreme muzzle energies are needed in a lightweight package for only a few shots.
The rails of a railgun are protected by a conductive carboplast sheath, which takes the punishment from firing rather than the main superconductive current-carrying layer or the structural support mechanism.
The sheath is rated to last for the discharge of one full magazine, after which is is recommended for the sheath to be discarded and replaced.
Usually, rail sheaths and ammunition magazines are packaged together and swapped out as a single unit. This makes reloading a railgun more expensive and cumbersome; spare ammunition is much more bulky because the rails are nearly as long as the railgun itself. In addition to the difficulties in carrying the ammo, reloading takes longer – inserting the sheath and magazine combo into a railgun takes five actions.
Railguns launch flechette dart penetrators similar to those of needlers. They have all the same ammunition options.
| Blast||-3½ RS||(7)||-2||+5|
| Blast||-3 RS||(7)||-1½||+5|
| Blast||-1½ RS||(7)||-½||+5|
| Blast||+1 RS||(7)||+½||+5|
- Partisan Railgun: This is a low-cost weapon often used by cash-strapped individuals or organizations that need a way to take out people in heavy armor. Unlike the other railguns listed here, the magazine can be swapped independently or the rails if a quick reload is needed.
On the second magazine (or corresponding number of shots) a given rail sheath is exposed to, the Spread score drops by 3 and the railgun will fail on a roll of 12 on 2d6 for each shot.
Each additional magazine decreases the Spread score by another 3 and the target for failure by an additional 1: 11+ on the third magazine, 10+ on the fourth magazine, and so on.
Swapping in a new rail sheath resets the counter – you get a full failure-free magazine at the original Spread, then start at the top of the sequence with a failure target of 12 for the next magazine and so on.
If the rail sheath fails, it will not work until the railgun is repaired, which requires 8 kiloseconds (2 hours) of work, parts that cost 1⁄10th the cost of the gun, and a DC 7 Fix and Build (mechanic) roll.
A failure by four or less wastes the time but not the parts; five to seven degrees of failure wastes the spare parts and eight or more degrees of failure destroys the gun.
Flechette: 3.5 × 40 mm
Energy per shot: 20 kJ
- Sniper Railgun: A large longarm with enough accuracy and hitting power that it is often used in sniper roles.
Flechette: 4 × 50 mm
Energy per shot: 30 kJ
- Anti-Materiel Railgun: A heavy railgun designed to take out equipment and vehicles. It is large enough that it is typically fired while prone, using a bipod.
Flechette: 5 × 80 mm
Energy per shot: 80 kJ
- Battlesuit Railgun: A large railgun for powered armor.
Flechette: 7 × 100 mm
Energy per shot: 200 kJ
- Railcannon: Cannons for applications where only a few shots are expected, but where each shot needs to hit extra hard.
- Small Railcannon: Rifle-configuration variants with a bipod are often carried by heavy battlesuits.
Flechette: 10 × 150 mm
Energy per shot: 500 kJ
- Light Railcannon:
Flechette: 12 × 180 mm
Energy per shot: 1 MJ
- Medium Railcannon:
Flechette: 18 × 300 mm
Energy per shot: 4 MJ
- Heavy Railcannon:
Flechette: 25 × 1000 mm
Energy per shot: 30 MJ
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