For other weapons with similar names, see here.

The Heavy Railgun v04 CS-OneSOneK (usually called the Heavy Railgun) is a powerful rail weapon made by the Civil Security. It is one of two railguns, the other being the Lite Railgun v01 CS-HShot. The Heavy Railgun has greater damage and power but slower speed and less accuracy than its cousin. As a rail weapon, it fires a high-damage beam with near-infinite speed, killing most enemies in one shot. It is a common weapon in the campaign, being used by enemies of all ranks and factions.

The Heavy Railgun has an incredible ability to cause stability loss to a target, and is helped by the fact that rail projectiles cannot be deflected by PSI Blades. This gun's weakness include a long reload time, the inability to go through walls, and slightly less accuracy than other weapons in its slot. The Heavy Railgun CS-OneSOneK has the highest single-projectile damage in the game, both in Multiplayer and the Campaign.

A fully upgraded Heavy Railgun can kill most enemies in the campaign in a single shot, especially when aimed to the head. When fully upgraded, it can kill the player in a single shot as well, and is the only weapon in the campaign able to do so. The gun is actually very common in the campaign unlike other high-damage weapons, possibly more common that the Lite Railgun. Unfortunately, the Marine can't use it until the later levels of the game and can't buy or upgrade it. However, Proxy can buy and upgrade the weapon.

When used against the Marine, however, this weapon is highly considered to be one of the cheapest in the game. At level 2 and onwards, it is easily capable of killing the Marine in one shot, especially if the shot happens either next to a wall, or if it is a headshot.

This gun is a very valuable tool when the need arises to kill exposed enemies very quickly. It cannot be dodged, as the projectile of the Heavy Railgun reaches its target instantly. The Heavy Railgun reloads when holstered, so other weapons can be used during the reloading process, an effective attribute. In multiplayer, the Heavy Railgun's projectile can bounce off of walls and surfaces, making it possible to overcome its lack of penetration in some instances. Skilled players can hit enemies by carefully aligning a series of reflections; a reflected rail can also kill the shooter.


Screenshot 497

The heavy railgun right after the shot.

The Heavy Railgun is first encountered in the campaign when a few Android SLC-56s equipped with it fight the player on Level 8. The gun is seen on a regular basis after level 8, usually upgraded to at least level 2. It cannot be picked up by the Marine or bought from the equipment shop. However, Proxy can pick up the weapon in level 30 from a crate and upgrade it in the equipment shop of Proxy. A fully upgraded Heavy Railgun can be picked up by any protagonist from a killed Civil Security Boss on level 40. The Marine may also obtain the weapon from Proxy as early as Level 37 by having Proxy drop the weapon for the Marine to pick up. (You'll have to get another heavy railgun for Proxy later on, however) This gun costs $2700 credits, and can be upgraded for $900 credits. The Heavy Railgun is moderately more expensive than the Lite Railgun.



An example of what the Heavy Railgun at level 30 can do.

  • It sacrifices speed for power, compared to its smaller cousin.
  • This gun's beam has a powerful knockback that can cause enemies to take additional damage if they're right next to a wall.
  • If you jump and shoot the Heavy Railgun, it may throw you back some distance because of its pounding recoil.
  • The Heavy Railgun can penetrate up to four bodies owing to its high projectile power.
  • The ID for the Heavy Railgun CS-OneSOneK is gun_railgun2
  • This weapon's rounds are extremely dangerous if rebounded off of a wall, as this can sometimes kill the player.
  • Although the railgun's speed appears to be infinite on land, it moves about as fast as a Plasmagun's pellet underwater. This suggests the projectile speed is extremely high, but not infinite. The same can be said for the Lite Railgun. 
    Screenshot 2016-03-05 at 3.30.05 PM

    Firing the Heavy Railgun underwater.

  • The bulb on its upper-rear will start to glow as the gun reloads; a pure blue indicates the reloading process is complete. 
  • Sometimes the railgun will not inflict full damage on its target, instead maiming him/her and leaving them in a dying state.
    • This seems to happen more with higher upgrade levels.
  • When the game is paused while the bullet is moving underwater, the glow will fade and reveal that the railgun bullet is actually very small, possibly the smallest in the game
  • While the Railgun's shots do not seem to bounce off of surfaces as much in campaign, in multiplayer it is infamous for its ability to bounce off of almost every surface.
  • When it is upgraded to level 3, it may sometimes make you become unstable due to its recoil power.
  • The letters OneSOneK may be short for One Shot One Kill, most likely a reference to its power.


  • Due to this gun's powerful and intense beam, it can make enemies bleed a lot. (The Lite Railgun does the same, but less.)
  • On Impossible difficulty, all Heavy Railguns upgraded to level 2 or 3 will be replaced by the Sniper Rifle CS-YippeeKiYay, except the player's. This is most likely because that, while the sniper is a weaker weapon with deflectable projectiles, the player's low HP voids any need for weapons as insanely powerful as the Heavy Railgun.
  • Because the Heavy Railgun fires a stream (instead of a bullet), it is much more effective against lagging players than the Sniper Rifle CS-YippeeKiYay and other bullet weapons.
  • It has the highest projectile power of all weapons in the game with a projectile power of 8. This is significantly higher than the runner-up, the Sniper Rifle, with a projectile power of 5.

Abnormally high accuracy as a result of hitting multiple targets.

  • It is used by all ranks of the Civil Security, and almost every Usurpation rank besides the minor, as well as the Android SLC-56. It is the only Civil Security weapon to be used by all ranks of the Civil Security.
  • It does a large amount of damage to Corvettes.
  • It features a distinct low hum when firing.
  • By striking more than one enemy at a time with a single shot, it's possible to attain abnormally high accuracy results.