Gauss

"Only my RAILGUN can shoot it."

– fripSide (A Certain Scientific Railgun)

FIRST AND FOREMOST: It is pronounced such that it rhymes with "house".

I'VE BROUGHT SCIENCE!

Gauss is the last name of Carl Friedrich Gauss, one of the greatest mathematicians in history. His work in calculus was (and is) invaluable to the study of electromagnetism, so he got a unit of magnetic field strength named after him. It is universally agreed that "Gauss" is a cool name, and so you can bet dollars to donuts that any sci-fi gizmo with any sort of vaguely electromagnetic theme will have the word "gauss" in it.

By the way, if an electromagnetic weapon doesn't have "gauss" in its name, it's a fair bet that it has the word "Tesla" in it, after another cool-sounding unit of magnetic field strength, itself named for Nikola Tesla, a famed inventor and scientist who did cool stuff with electromagnetism.

"Realistic" gauss weapons come in two flavours: rail-guns and coil-guns. Rail-guns (which are often mistakenly called "Gauss guns" in poorly researched sci-fi for the simple fact that both are electric guns) work by having a really long pair (or pairs) of conductive rails within the barrel, with a positive pole on the receiver end of conductor A, a negative pole on the receiver end of conductor B, and an electrically conductive projectile. When the projectile is placed and the railgun switched on, electricity flows through conductor B towards the end of the barrel, passes through the projectile, and returns in the opposite direction through conductor A, creating two magnetic fields of identical polarity around them. This makes the projectile act like a current-carrying wire in a magnetic field, which means the projectile experiences a Lorentz force that moves it forward, like an electric motor that is unwound into a straight line; this one is in theory cheap to manufacture and capable of reaching awesome velocities, at the cost of being energy-hungry, needing to be really long and causing a lot of stress on the materials. It's not to be confused with the Peasant Railgun. Coil-guns work by surrounding the barrel with a sequence of coil magnets that are switched on to pull (and then reverse current to push only pull because that's how magnetic response works in materials) the projectile. Since the projectile doesn't physically touch the mechanisms touches the barrel for ballistic reasons but isn't trying to spot weld itself to it, the gun lasts longer and there is better control over the speed, but the control mechanisms are very complicated and the overall weapon is weaker than a railgun of the same current draw has better theoretical efficiency but experiences high losses at higher muzzle velocities due to switching speed and timing issues. Of course, once you get into soft sci-fi, all bets are off; expect to see guns that shoot lightning.

When used as a name, "Gauss" is capitalized. When used as a unit or adjective, "gauss" is usually lowercase (though the abbreviation for the CGS unit is a capital "G").

Real-Life

Who needs fiction when weapons this badass exist?

Now capable of automatically loading rounds for letting out salvos.

Ahhhh....looks like we are at the beginning stage of the Imperium of Han.

"Velocitas Eradico" - "I, Speed, eradicate."

– Motto of the United States naval railgun development program

The US Navy has successfully tested 32-megajoule railguns. The friction from the ammunition moving at these velocities turns the air inside the barrel into plasma instantly. They were planning to build a 64-megajoule gun to test fire, but they lost funding. This might have to do with how they had to build an entirely new railgun after every third shot; the rails wear out quickly due to the heat the projectile produces, and no known material is heat-resistant enough to withstand being worn out in this manner and also capable of conducting electricity to allow the mechanism to work in the first place ohmic heating combined with the mechanical effects of the projectile continually welding itself to the rails while the electromagnetic forces apply enough force to accelerate it anyway. You also need a really strong generator fast discharge power storage system to provide enough power to operate the weapon. In any event, nobody foresees those problems the rail destruction issue being solved anytime soon. Then again, the first flight occurred in 1903 and Sputnik was launched in 1957 (giving a difference of 54 years, well within a modern human's lifetime) so make of that what you will. Update: Recent reports have indicated that the rail destruction problems are getting better. They can now fire them about 400 times before having to replace them. Granted, the navy really wants a minimum of 1000 shots so they're still not at a level they want yet. But that's still an amazing efficiency upgrade, and in a pinch 400 time's is probably still combat viable since an Alaska cruisers main gun's lasted about 344 shots.

On early February 2018, pictures showed that China became the first nation to mount a railgun on a naval warship. The Chinese People's Liberation Army Navy claims to have solved the power supply problem after extensive testing, and current intelligence reports suggest that Chinese warships could be equipped with railguns as early as 2025. The reports also note that the railgun is said to have a maximum range of 125 miles and fire shots that travel seven times faster than the speed of sound. Further sightings of Chinese warships equipped with railguns in 2019 have brought up the possibility that large scale field testing may begin within a year.

If you see a carpenter using an "electric nailgun," it's likely not actually a coilgun they're using, unless they have a "Solenoid-powered nailgun", which are single-stage coilguns.

Some consideration has been given to using gauss accelerators for space launches. Instead of building a bunch of rockets that you need to fuel, repair, maintain and discard you use as sequence of electromagnets to speed up a payload bit by bit until it reaches orbital velocity. Especially if you are on the moon or some other body without an atmosphere, this could be a good dependable option.

Rifts

In Rifts, a "Gauss cannon" is just a synonym for "machinegun that does MDC damage." The artwork for railguns always shows them as ejecting casings and being round, with no rails in sight ... it's not like anything else in Rifts even tries to be rational, so just roll with it.

Alternate take: Gauss guns don't have rails and may look like guns with really beefy barrels (probably so if the electronics are armored. That doesn't explain the casings though. Actual railguns use a gunpowder charge or similar effect to get the projectile going since it will weld itself to the rails and stay there if it initially touches them at low speed or is already in contact when current is applied.

Traveller

In Traveller, Gauss weapons are slugthrowers that use 3-5.5mm (.11 to .21 calibre) slugs or flechette needles. They're the preferred rifle and sidearm for TL12 armies (Tech Level 10 in GURPS Traveller); at this tech level, the preferred heavy weapons will be laser or plasma. Until these non-chemical sidearms are in use, ship boarding parties in space prefer using sabres and melee for combat. The exception is zero-G environments, where recoil on any slugthrowers (gauss or not) are as much a hazard for the wielder as the target.

Warhammer 40,000

The only thing that made the old Broadsides different from the normal battlesuits were the huge Twin-linked strength 10 AP 1 guns.

Being set in the grimdark future, several Warhammer 40,000 races use Gauss weapons.

Tau

The Tau use railguns as the primary heavy weapons on tanks and walkers.

Rail Weapons are considered some of the most potent and fearsome weaponry employed by the Tau Empire. Rail weapons are linear accelerators that use super-conductive electrodes to accelerate a solid-shot round to hypersonic speeds. The vast kinetic energy generated by the round on impact is capable of devastating damage on enemy vehicles.

Usually, Rail weapons are (obviously) very powerful and capable of extreme penetration (as in real life) as the acceleration is limited only by the amount of power that can be input and how much the weapon can handle without exploding or melting.

Rail Rifle

Rail Rifle

Emboldened by the success of vehicle-mounted railguns, the Earth Caste built a Tau-portable railgun weapon, called the "rail rifle." It debuted in Warhammer 40,000: Fire Warrior as a prototype weapon; it soon got rules in Chapter Approved, and by the next Tau Empire Codex, it was a regular part of the Fire Caste's armory, used by Pathfinders and drones as a sniper weapon. Incidentally, while it was in Chapter Approved, the Rail Rifle was subject to "Gets Hot!" like a Plasma Gun, but the Earth Caste improved the safety margins on it such that blowing up in the user's face is no longer a concern by the time of the 4th Edition codex. 6th edition further uplifted the rail rifle, turning it from Heavy to Rapid Fire and making it AP1, meaning it now could oneshot terminators and light vehicles, be fired on the move and even could be fired in full-auto.

It is mentioned in the fluff that once Rail Rifles are advanced enough to mass-produce and do not eat all the ammo and battery pack in a matter of seconds (and seeing their progress rate from overheating backpack-powered heavy weapon to magazine-fed rapid fire rifles in a matter of a few decades it's not a long time to wait for), Tau command have plans to use them as standard issue Fire Warrior guns instead of pulse rifles. Come 8th edition they are still used only by Pathfinder teams. At least until a new Tau Codex comes out. If GW did do this they would either likely nerf its range to match up with the Lasgun and Bolter and increase the price to the same as a Plasma Gun, OR give it to an elite new Tau unit analogous to the space marine Sternguard since, logically, a new weapon would not be available in large enough numbers for the whole army as they just started mass production so best give it only to the elites. Otherwise it would pretty much break the game with Tau basic infantry being able to steamroll everything in their field of view even more than 3E Necrons could. One would think that this would be possible as the Tau now have Plasma Shotguns but they remain one of the few races without a one man flamer.

Heavy Rail Rifle

Heavy Rail Rifle

A recent development wielded by next-generation Broadside battlesuits, it is less powerful than the Tau's primary railguns, though only moderately so (S8 versus S10). However, its reduced bulk allows it to be mounted in such a way as to more easily track fast moving targets, and thus it fulfills an anti-air role, where its slightly reduced strength is not a big liability as it is still plenty powerful enough to punch through most fliers with ease, and its double-barreled (twin-linked) setup increases its odds of hitting a target rather than its odds of wounding or total wounds deal after wounding. That said, it's still a considerable threat even to AV13 vehicles, since with AP1 the first penetrating hit would likely be the last.

Railgun

Railgun

The Railgun is the iconic Tau heavy weapon, mounted on Hammerhead Gunships (and Battlesuits, in previous editions) to cause massive damage to enemy armor (72", S10, AP1). At its most basic form the railgun is a linear accelerator using standing wave acceleration along a number of cylindrical superconductive electrodes surrounding a barrel (duh).

A Broadside Battlesuit Team used to be able to carry up to 3 twin-linked railguns in one Heavy Support slot (nerfed to the S8 heavy rail rifle, see below, in their 6E codex), while the Hammerhead can only carry one, but the Hammerhead has enough ammunition capacity to also carry a S6 AP4 Large Blast submunition round for dealing with infantry blobs. (Squad of guardsmen a turn anyone?)

With the 9th Edition Tau Codex coming out soon these guns got a humble buff to 72" S14 AP-6 D1d3+6 WITH AND ADDITIONAL FLAT 3 MORTALS WITH THE ENTIRE GUN ALSO IGNORING INVULNERABLE SAVES AND GETTING A REROLL TO HIT! Knights tremble before this gun and hide behind their terrain, praying to Big E that the tank it's attached to looks the other way. Though the stats are pretty damn good, Broadsides (with the Heavy Rail Rifle) outperform it when you throw in point costs. This makes the Railgun more of a psychological tool to strike fear into the previously mentioned Knights.

Heavy Railgun

Heavy Railgun

Because the regular railgun wasn't enough for putting down the really big targets (like Titans), the Earth Caste developed the Heavy Railgun (110", SD, AP1) for their super-heavy vehicles. It was originally designed to blow up space ships, as Tau never expected anyone to be stupid or crazy enough to build a big enough land-based vehicle to justify this weapon's use against it.

Then they encountered Ork gargants and Imperium titans, and figured out that most inhabitants of the Galaxy aren't sane or reasonable. The Manta mounts two of these, while the Tiger Shark AX-1-0 mounts a twin-linked pair. Like the Hammerhead railgun, the heavy railgun can fire a pie-plate for destroying massed infantry formations, but the heavy railgun's submunitions are S7 AP3 and the blast is 10" across.

Heavy Rail Cannon Array

Heavy Rail Cannon Array

The latest advancement in bringing hyper magnetized death to the enemies of the Greater Good. The Heavy Rail Cannon Array is mounted on the KX-139 Ta'Unar Supremacy Armour, and is designed to take down Super-Heavy vehicles and Gargantuan creatures, alongside any infantry which may be attempting to close in on the suit.

The Heavy Rail Cannon itself possesses a longer range than the equally destructive Heavy Railgun topping out at 120", S:D AP1, Ordinance (1), Blast (3") however it has been designed to aim at the heaviest points of an enemy and strike those points with enough force that should it wound the enemies own mass is turned against itself (roll twice on the Destroyer Weapon Attack table and pick the higher result when firing against Super Heavies or Gargantuan Creatures), and is paired with the Cluster Shell system which is used to launch sub-munition shells at nearby enemies (36", S:6 AP4, Apoc Barrage (4), pinning), in such a way that both weapons may be fired against different targets at the same time.

Starship Railgun

Starship Railgun

Exceptionally large and heavy Railguns mounted on the biggest Weeaboo vessels.

Starship Railguns are the primary weapons for the Kor'Vattra. Their ease of construction and maintenance of Railweapons among the Tau means that eventually, they were gonna supersize this and call it a day.

All/most Starship-level Railguns are twin-linked for twice the shooty power.

Due to how common and ubiquitous these weapons are, these Railguns are analogous to the Imperial Macrocannons, except, in a display of common sense, the Tau actually thought it was a good idea to mount them on a turret to fire anywhere, rather than restricting it to 17th century-level static broadsides. The primary advantage of this is that it allows Tau ships to basically fire anywhere, leaving no blind spots unlike the Imperial, Eldar, Dark Eldar, Orks or Chaos fleets. The downside of this is that because of the turret, they could not be compacted as much as Macrocannons, meaning that there are fewer Railguns per-ship than usual, ergo less Dakka.

Heavy Starship Railgun

Heavy Starship Railgun

Because of course the fish faces didn't stop at just a ship-sized Railgun. For when they want to punch through something neat and clean, the Heavy Starship Railgun is a much bigger and longer weapon than your typical Starship Railgun.

Owing to its longer barrel, the Heavy Starship Railgun are the largest version of Railweapon mounted on larger Tau spacecraft. Its size means that it can't be twin-linked, but it also means that it has a longer range and hits twice as hard. Only 3 Heavy Starship Railguns could be mounted on the largest of Tau Merchant Battleships as they are the only ones with the power to use these things in numbers.

Like its smaller brethren, it is mounted on a turret which allows it to hit anywhere. Although considered their analogue of a Nova Cannon, the Heavy Starship Railgun does not deal the same level of catastrophic explosion as its Imperial counterparts, rather, trading balls-out firepower with consistent shooting and accuracy.

Weapons of the Tau Empire
Sidearms:
	Ballistics:	Kroot Pistol
	Directed-Energy:	Pulse Pistol
Basic Weapons:
	Ballistics:	Kroot Scattergun - Kroot Rifle - Krootbow
	Directed-Energy:	Pulse Blaster - Pulse Carbine - Pulse Rifle
Special Weapons:
	Ballistics:	Accelerator Bow - Kroot Bolt Thrower - Kroot Gun Kroot Hunting Rifle - Londaxi Tribalest - Rail Rifle
	Directed-Energy:	Ion Rifle - Neutron Blaster
	Other:	Dvorgite Skinner
Battlesuit Weapons:
	Ballistics:	Airbursting Fragmentation Projector - Flechette Discharger - Heavy Rail Rifle - Missile Pod
	Directed-Energy:	Burst Cannon - Cyclic Ion Blaster - Cyclic Ion Raker - Fusion Blaster - Fusion Cascade Fusion Collider - Heavy Burst Cannon - Phased Ion Gun - Plasma Rifle
	Incendiary:	Tau Flamer
Heavy Battlesuit Weapons:
	Ballistics:	Fragmentation Cluster Shell Launcher - High-Yield Missile Pod
	Directed-Energy:	Heavy Burst Cannon - Ion Accelerator - Ionic Discharge Cannon Long-Barrelled Burst Cannon - Pulse Submunitions Cannon Pulse Submunitions Rifle
	Incendiary:	Phased Plasma Flamer
Vehicle-mounted Weapons:
	Ballistics:	Railgun - Seeker Missile - Smart Missile System
	Directed-Energy:	Ion Cannon - Tau Plasma Cannon - Pulse Bomb Generator Quad Ion Turret - Fusion Cannon
Super-Heavy Weapons:
	Ballistics:	Cluster Rocket System - Destroyer Missile - Heavy Rail Cannon Array Heavy Railgun - Nexus Meteor Missile System
	Directed-Energy:	Ar'Ka Cannon - Fusion Eradicator - Pulse Blastcannon Pulse Driver Cannon - Pulse Ordnance Multi-Driver Tri-Axis Ion Cannon
Ship Weapons:
	Ballistics:	Torpedo - Starship Railgun - Heavy Starship Railgun Gravitic Launcher - Warsphere Missile Pod
	Directed-Energy:	Cutting Beam - Heavy Ion Cannon
Non-Firearm Weapons:
	Melee Weapons:	Bonding Knife - Equaliser - Honour Blade - Onager Gauntlet
	Grenades & Explosives:	EMP Grenade - Photon Grenade

Necrons

Truer words have never been said.

The backbone of the Necron force are nominally gauss weapons which produce a magnetic field with the strength of several thousand Teslas. And then point it at something they don't like. They do this by producing an incredible voltage across the body and focus of the gun (hence its electric nature. Doesn't explain the green though.) and then driving a current across it using two charge-rich microdimensions (think Rick Sanchez's spaceship's battery), one in the focus and one in the body. The focus limits the volume effected since it's bad form to destroy everything around you including allies, enemies, rocks, atoms, yourself etc. The process is not perfect however, since charge fluctuations in the microdimensions translates to a varying strength of field which expresses itself as a non-uniform level of destruction from one moment to another. One second it can melt a Land Raider, the next it might just have enough for a butterfly. You know, if you found butterflies in the middle of a Necron battleline. The third edition codex described the effect as a "beam" that instantly "pulled" the target towards the gun, one layer of molecules at a time. This gave the effect of flaying the target and the more powerful the gun, the quicker this happened and the more layers of molecules that were flayed with each shot. The beams are capable of stripping away almost anything, even ceramite armor and starship hulls, with ease.

(Most sources don't bother with this fluff and just have Necron Gauss weapons fire distinctly un-Gauss disintegration rays in the form of green lightning.)

In the Third Edition Codex, Gauss weapons automatically wounded infantry and automatically caused glancing hits to vehicles on a to-hit roll of 6. This was devastatingly powerful at the time, as it meant that Necrons could chew through vehicles like no tomorrow, but was rather reduced in effectiveness in Fifth Edition, as most vehicles could no longer be destroyed through glancing hits alone, though with the introduction of Hull Points in Sixth Edition, Gauss weapons are once again a lot more dangerous to vehicles (three glancing hits -- which a full squad of 20 Necron Warriors can easily supply -- is enough to wreck most regular vehicles and expose a super-heavy ). That said, Gauss weapons were reduced in effectiveness by the Fifth Edition Codex, which removed the auto-wound property (anti-infantry effectiveness was moved to their new "Tesla" weapons). However with the advent of the 7th edition codex Gauss weapons have regained their auto-wounding on 6's, which wasn't much of a buff since those weapons already did wound on a 6 in most cases, leaving that rule only being useful against Gargantuan Creatures.

The closest thing IRL to Necron Gauss weapons are Plasma Railguns. Which shoot Ionized Gas instead of a solid slug. But don't expect BL writers or Games Workshop to use Google in order to fix their inaccuracies.

Gauss Flayer

Gauss Flayer

The trusty Gauss Flayer is the standard weapon (in fact, the only weapon(until the 9th edition that is)) wielded by Necron Warriors. Gauss Flayers are rifle-like weapons used by Necron Armies. They consist of a metal stock, a transparent tube containing the unholy and unknown energy the weapon fires, and an axe-like bayonet underneath the muzzle.

The weapons fire green, lightning-like beams at the enemy, which strip the targets away molecule by molecule. It is, supposedly, extremely painful to be shot with a Gauss Flayer, and victims die as much from shock as the damage caused by the beams. The Gauss Flayer as pictured on the right, had the classic green rod look before it was superseded in 9th Edition by the more ornate type present in the other examples.

Its stats are equivalent to the bolter, with the additional "Gauss" rule mentioned above. Ghost Arks and Doomsday Arks mount an array of five of these guns on each side, while the Canoptek Doomstalker has a single pair of them for self defense.

Gauss Reaper

Gauss Reaper

A Gauss Flayer with two barrels that is differentiated from the Gauss Blaster by having the barrels be much shorter. The tradeoff is that it sacrifices range for increased hitting power. Despite its looks, it should NOT be confused with the Gauss Blaster.

Introduced in 9th as a alternative weapon for Necron Warriors, it possesses an extra pip of strength and AP in exchange for being Assault 2 with a range of 12" (i.e. the same as the rapid fire mode of the Gauss Flayer). This makes it a better fit for deep striking groups of warriors intending to get dropped in the backside of the enemy to roast them with green fire. For your mainline warrior blobs, it's more of a debate as getting all of them in range from the middle of the field is a greater hassle, and significantly weaker fire is better than no fire. Thankfully, you can mix and match within the unit.

Until you consider the fact it has no cool axe head or proper beefy bayonet, which makes it objectively worse. At least it has 2 prongs.

Gauss Blaster

Gauss Blaster

A Gauss Flayer was given the Multi-Melta treatment, that is, get two of the same gun and then MacGyver all over it.

The Gauss Blaster is the standard weapon of Necron Immortals; Gauss Blasters fire more powerful beams than Gauss Flayers, and are extremely potent against infantry and light vehicles alike. Despite its looks, it should NOT be confused with the Gauss Reaper.

Necron Pariahs also make use of a form of in-built Gauss Blaster integrated into their Warscythes. Unfortunately, Pariahs no longer exists thanks to this loser, so the days of Warscythes-Gauss Blaster combo is a thing of long lost past.

It is basically a Gauss Flayer with slightly improved strength and armor-piercing capability (FOUR microdimensions, for when you need several universes to simultaneously hate the same thing). A unit of Tomb Blades can also choose to take twin-linked pairs of them to specialize in vehicle-hunting.

Gauss Cannon

Gauss Cannon

The iconic weapon of Necron Destroyers is their shoulder-mounted Gauss Cannon, however, both Catacomb Command Barges and Annihilation Barges are able to mount an underslung Gauss Cannon instead of their usual Tesla Cannon. In addition, Tesseract Arks can mount a pair as sponson guns, for extra MEQ-killing power.

Though it's only as strong and long-ranged as a Gauss Blaster, it is overall a larger version of the Gauss Blaster and has four barrels, providing it with an even higher rate of fire and because of its mounting on a heavier base, it has greater power over a greater distance. Also due to its mount it is able to be fired and redeployed very quickly. It has more shots and will tear through all but the toughest armor suits.

Gauss Destructor

Gauss Destructor

A new weapon found in the Lokhust Heavy Destroyer. The Gauss Destructor seemed to largely replace the Gauss Cannon or Heavy Gauss Cannon as its spiritual successor. Unlike its predecessors, the Gauss Destructor is not shoulder-mounted, instead, it is held by three hands like any Genestealer heavy weapon.

On the tabletop in 9th Edition, the Gauss Destructor is the Lokhust Heavy Destroyer's primary anti-tank option. It is a 36" Heavy 1 weapon that is S10 and AP-4. This stats allow it to breach any hull of any vehicle, up to and including, superheavies. It also makes any unit that does not have a 2+Sv to take an instant wound, so there's that too. It deals 3D3 damage, so have fun throwing - on average - 4-6 wounds per shot.

Heavy Gauss Cannon

Heavy Gauss Cannon

Necron Heavy Destroyers get Heavy Gauss Cannons, and Triarch Stalkers can choose a twin-linked set of them as a primary weapon. They only get one shot, but it's as powerful as a lascannon.

These Gauss Weapons have been known to hurt monstrous creatures that similar weapons have no hope of even scratching, and have also been documented tearing at the armour of even the most heavily armored of tanks and starship hulls with ease. The Imperium of Man is confounded by the nature of the energy used by these weapons, not only because the basic weaponry of the Necrons can cause great harm to even the most advanced vehicles deployed by the armed forces of the Imperium, but also because by all the physical principles known, these weapons should overheat and malfunction as a result of the tremendous energies they unleash, destroying the warrior who is firing them.

It is a larger version of the Gauss Cannon, although it only has one barrel and so a slow rate of fire. Though it has the greatest power and range, its reduced rate of fire makes it less effective against vast armies, but more effective against certain heavily armored targets, such as Land Raiders.

So when people meant that the Necrons can blow up your Land Raider with their most simple weapons, this is the gun they usually specify.

Gauss Flux Arc

Gauss Flux Arc

The Gauss Flux Arc is basically like the Gauss Flayer, but firing more shots at a time by simply opening one enormous microdimension. Monoliths mount one at each corner, Ghost Arks mount one at each side, and they are capable of choosing their targets independently. Gauss Flux Arcs come in the form of four automated turret projectors positioned around the vehicles hull.

Gauss Flux Arcs consist of linked batteries of three Gauss Flayers, which each feature a single barrel that leads to a transparent conduit containing the unholy and unknown viridian energy the weapon fires, and an axe-like bayonet underneath the muzzle (even though the weapon is connected to a platform that would make the use of the bayonet pointless in the first place).

Gauss Exterminator

Gauss Exterminator

A Gauss Exterminator is a large Gauss Weapon mounted as the primary weapon on Necron Sentry Pylons. Similar in power to a Heavy Gauss Cannon, a Gauss Exterminator possess a higher rate of fire and is able to engage targets at extreme ranges. Gauss Exterminators are also capable of using their sophisticated targeting systems to accurately track and fire upon aircraft at incomprehensibly long ranges.

Exterminators are far larger than the more common Gauss Flayers, Gauss Blasters and Gauss Cannons, and feature a single elongated barrel containing the unholy and unknown viridian energy the weapon fires.

In 9th Ed, Gauss Exterminators are good for flyers and ground support with two S12 shots. Although it lacks the +1 to-hit against non-FLY units, the Gauss Exterminator shoots twice - so it has a better chance of landing at least one shot, and can also land two (and has +1 to hit vs FLY).

• 

Gauss Annihilator

Gauss Annihilator

Basically an upscaled Gauss Exterminator, but instead of aircraft, it's everything.

A Gauss Annihilator is one of the largest known forms of Gauss weapons, with the only Gauss weapon similar in size to it being the Gauss Obliterator. Gauss Annihilators are only ever found mounted on devastating Necron Gauss Pylons.

Like the smaller Sentry Pylon, the shape of the both the weapon and machine itself is quite identifiable. A Gauss Annihilator consists of a single focusing crystal which leads to transparent tubes containing the unholy and unknown viridian energy the weapon fires. This is combined with several focusing arrays and a pair of particle emitters mounted on the Pylon's crescent shape to further empower the Gauss Annihilator beams.

Gauss Annihilators are supremely powerful weapons, capable of a relatively fast rate of fire that can penetrate even Titan armor with ease; let alone vaporize smaller tanks. With good reason, too: in fluff these things are ground-to-orbital weapons with enough hurt to cripple cruisers in a single hit. Gauss Annihilators can also be fired as a flux arc similar to the Gauss Flux Arcs mounted on a Monolith. However, a Pylon's version is stronger and can even destroy Space Marines with comparable ease in a larger radius; as Gauss beams lance out all around it.

Gauss Obliterator

Gauss Obliterator

The glowing crystal of doom.

A Gauss Obliterator is one of the largest known Gauss weapons, with the only Gauss weapon similar in size to it being the Gauss Annihilator. Gauss Obliterators are only found mounted on the Doomsday Monolith variant, where the weapon itself consists of a large focusing crystal leading to transparent conduits containing the unholy and unknown viridian energy the weapon fires.

Doomsday Monoliths can focus their awesome destructive energies into devastating beams which can be fired from its Gauss Obliterator; the beams themselves are capable of outright destroying infantry and vehicles alike. However, a Doomsday Monolith is inevitably accompanied by several lesser constructions, whose eldritch power it can siphon towards its own cataclysmic ends. This additional energy is drained from the power matricies of other Monoliths, and is discharged from the Gauss Obliterator in the form of additional blasts. This increases the weapon's rate of fire and all but ensures the doom of the enemy.

Unfortunately, despite receiving a model, the Gauss Obliterator along with the Doomsday Monolith have not received any rules. Nevertheless, one could estimate that thing monstrosity would be the equivalent of a Volcano Cannon.

Weapons of the Necrons
Sidearms:
	Ballistics:	Tachyon Arrow
	Directed-Energy:	Enmitic Disintegrator Pistol - Particle Caster - Scouring Eye
	Dimensional:	Transdimensional Beamer
Basic Weapons:
	Directed-Energy:	Gauss Flayer - Gauss Reaper - Tesla Carbine
Special Weapons:
	Incendiary:	Gauntlet of Fire
	Other:	Synaptic Disintegrator
Heavy Weapons:
	Directed-Energy:	Gauss Blaster - Gauss Cannon - Gauss Destructor - Heavy Gauss Cannon Particle Beamer - Enmitic Annihilator - Enmitic Exterminator
Staff Weapons:
	Directed-Energy:	Arcane Conduit - Eldritch Lance - Entropic Lance Rod of Covenant - Staff of Light - Staff of the Destroyer Voltaic Staff
	Other:	Abyssal Staff - Aeonstave - Empathic Obliterator Staff of Tomorrow - Tremorstave
Vehicle Weapons:
	Directed-Energy:	Death Ray - Focused Death Ray - Gauss Exterminator - Gauss Flux Arc Heat Cannon - Heat Ray - Particle Shredder - Tesla Cannon Tesseract Singularity Chamber - Thermal Cutting Beam
	Dimensional:	Exile Cannon
Superheavy Weapons:
	Directed-Energy:	Annihilator Beam - Doomsday Cannon - Doomsday Blaster - Gauss Annihilator Gauss Obliterator - Particle Whip - Tesla Destructor - Tesla Sphere - Æonic Orb
	Gravitational:	Singularity Generator
	Dimensional:	Transdimensional Projector - Transdimensional Abductor
	Other:	Synaptic Obliterator - Atomiser Beam Lance
Ship Weapons:
	Directed-Energy:	Lightning Arc - Particle Whip Launcher
Non-Firearm Weapons:
	Melee Weapons:	C'tan Phase Weapons - Hyperphase Weapons - Miscellaneous Weapons - Voidblade
	Grenades & Explosives:	Countertemporal Nanomine - Death Spheres

Eldar

Eldar in general do not make wide use of magnetic weaponry. Their Shuriken and Shard weaponry function similarly to magnetic weapons, but rather than using an electro-motive force they use miniaturized grav-generators similar to what keeps skimmer vehicles airborne (at least according to the 2nd Edition fluff on shuriken weapons which we have no reason to believe has changed.) Essentially, they make gravity inside the barrel point to the end of the barrel as "down" as though they were on a particularly heavy gravity well, and the rounds "fall" out through the end of the barrel with an intense acceleration, keeping their momentum once they align back with the normal gravity outside the gun.

Squat

The Squats makes extensive use of railguns in the Leagues of Votann, the majority of which rivals or just outright eclipses their Tau counterparts, because the Dorfs are just that good at making shit that lasts. Squats generally use railguns for more specialist units and vehicles due to the increase in maintenance and technical knowhow needed to make sure the weapons keeps on firing.

Magna-Rail Rifle

Magna Rail Rifle

Whilst the Tau are busy designing the prototype of their shoddy Magna-Rail Rifle knock-offs that could only be fitted on a XV88 Broadside Battlesuit, the Leagues are already mass producing these things millennia before the Tau even existed.

The League's Magna-Rail Rifle is designed as the primary sniper rifle of the Squats and is small and compact enough that it does not need an external powersource or a mech suit to power it up. The Squat's extensive knowledge and experience in rare magnetic materials make sure that the League holds all the good shit. If the similar development relationship between the Tau and the Squats in regards to this weapon is certain, then it is possible that the history of the Magna-Rail Rifle is similar to the Tau's own relationship with Ion weapons vis-a-vis the Squats.

So whenever the Tau manages to get their Magna-Rail Rifles working, it would already be several generations behind that of the League. Just As Planned.

On the tabletop, this translates to a 24" HunTR 1, S9 AP-4 Dd3+3 sniper rifle, and has the Magna-Rail keyword. Everything ridiculous about Tau railguns turned up to 11 and in a troop-portable package. Fills a similar role to the high strength/low shot weapons seen in other armies such as melta-guns and las cannons.

Magna-Coil Autocannon

Magna-Coil Autocannon

The similarly named Magna-Coil Autocannon is another weapon used by the Leagues.

Unlike the majority of the weapons listed here which are railguns and especially unlike the Necrons which is anything BUT Gauss. The Magna-Coil is a true gauss gun, with a capital G in its name. This coilgun is the primary weapon of the Magna-Coil Bikes and is mounted on the front of the vehicle. It features a drum magazine and fires bolts travelling at adjustable speed depending on the number of coils it is powering up.

Crunchwise, the weapon is a 24", HunTR 3, S 7, AP-1, D2 gun. Really fucking nasty against MEQs and TEQs and can even do a number on tanks if enough is landed on it. A single round of three Pioneers can quite realistically delete your entire Space Marine squad if its wants too. So yeah, not to be fucked with.

Heavy Magna-Rail Cannon

Heavy Magna-Rail Cannon

The Magna-Rail Rifle's beefier cousin.

The Heavy Magna-Rail Cannon is a type of heavy Rail Weapon used by Leagues of Votann Hekaton Land Fortresses. Seriously, think of everything already said about the rifle, and now dail-up the dial-up to 180, and you have a monster of a railweapon. These heavy beef cheesecakes are pound-for-pound the most powerful railguns for its size. Tau players eat your heart out.

Crunchwise, the tabletop kind of fits the fluff. This is the daddy of the Magna-Rail Rifle held by the Hearthkyn and probably the most dangerous single weapon in your arsenal. This is a 36" Heavy 1, S14 AP-4 D2d3+6 monster with Magna-Rail, and will likely ruin the day of anything it's pointed at.

Weapons of the Leagues of Votann/Squats
Sidearms:
	Ballistics:	Autoch Pattern Bolt Pistol - Bolt Revolver Ironhead Autopistol - Ironhead Bolt Pistol Ironhead Stub Gun
	Directed-Energy:	EtaCarn Plasma Pistol - Ion Pistol Las-Beam Cutter - Plasma Torch Stone Burner - Volkanite Disintegrator
	Incendiary:	Hand Flamer
Basic Weapons:
	Ballistics:	Autoch Pattern Bolter - Bolt Shotgun - Ironhead Autogun Ironhead Boltgun - L7 Missile Launcher
	Directed-Energy:	EtaCarn Plasma Beamer - EtaCarn Plasma Gun HYLas Auto Rifle - Ion Blaster
Special Weapons:
	Ballistics:	Chthonian Mole Grenade Launcher - Grenade Launcher Magna-Rail Rifle - Mole Mortar
	Gravitational:	Graviton Rifle
	Combi-Weapons:	Autoch Pattern Combi-Bolter
Heavy Weapons:
	Ballistics:	Bolt Cannon - Exo-Armour Grenade Launcher Ironhead Heavy Stubber - Magna-Coil Autocannon
	Directed-Energy:	HYLas Rotary Cannon - Ion Beamer - SP Conversion Beamer
	Gravitational:	Graviton Blast Cannon
Vehicle-mounted Weapons:
	Ballistics:	Hekaton VLS - MATR Autocannon Sagitaur Missile Launcher
	Directed-Energy:	Cyclic Ion Cannon - HYLas Beam Cannon
Ordnance:
	Ballistics:	Doomsday Cannon - Goliath Mega-Cannon - Thunderer Cannon Thunder-Fire Cannon
Super-Heavy Weapons:
	Ballistics:	Heavy Magna-Rail Cannon
	Directed-Energy:	SP Heavy Conversion Beamer
Ship Weapons:
	Ballistics:	Doomstorm Missile - Macrocannon - Torpedoes
	Directed-Energy:	Cutting Beam - Hellfury Cannon - Lance Weapon
Non-Firearm Weapons:
	Melee Weapons	Concussion Weapons - Grav Close Combat Weapons Force Weapons - Close Combat Plasma Weapons Miscellaneous Weapons - Squat Power Weapons
	Grenades & Explosives	C8 HX Charge - Gravitic Concussion Grenade

Imperium

Strangely enough, heavy bolters use coilgun tech to further accelerate its bolts, so they can use much lighter ammo with less gunpowder (as real life gyrojets have shown, more "kick" is needed to make it viable at ranges below a dozen or more meters).

Also, the NOVA CANNON is sometimes described as fuckhuege railgun, though this is only one of a half dozen completely different explanations of how the NOVA CANNON actually works. (which is actually surprisingly fluffy, when you think about it.) Macro Cannons, the Imperium's go-to for ship-to-ship broadsides each utilize a massive coil gun in the outer muzzle shroud to accelerate their shells even further.

Other possible Imperium Gauss weapons are Accelerator Autocannon of the Sicaran Tank, the Accelerator Cannon of the Fellblade and the Macro-Accelerator cannons on the Astraeus. If not they are gravity accelerated like Eldar Shuriken Catapults. Since all but the Astraeus are relics that even the most adept Techmarines and Tech Priests are too paranoid to mess with. Modifying these weapons for other platforms or using them like Havocs armed with Autocannons are unlikely. With Cawl being the sole possible exception.

For the record the Galvanic Weapons used by the Skitarii and Secutarii are not coil-guns despite the fact that the term implies it uses electric currents. The chemical reactions would mean that they are Electrothermal-chemical weapons powered by a battery.

Magnarail Lance

Magnarail Lance

Possibly the only known handheld Imperial rail gun (as of yet). The Magnarail Lance is one of the primary weapons of the Tech-Priest Manipulus, with the other one being the Transonic Cannon. The Magnarail Lance is an odd-looking railgun in all honesty. Resembling more like a harmonic pitchfork, the weapon is externally conducted by two electromagnetic rails, that launches the projectile within the barrel.

On the tabletop, the Magnarail Lance is an 18" Heavy 1 S7 AP-3 weapon that deals d3 damage or a flat 3 damage if the bearer did not move. Can go up to 21" range if you use the Manipulus' bolster weapon rule.

In contrast to the Transonic Cannon which deals with hordes at close range, the Magnarail Lance is designed to terminate vehicles and heavy armor from longer ranges. However, by doing so, it limits the Manipulator's other weapons and equipment which are all at close range.

StarCraft

In StarCraft, the main weapon of the Terran marines is a gauss weapon referred as the Gauss Impaler Rifle, and their design varies between the first and second games, where in the first they looked like pump action shotguns (big ones almost as tall as the user) while in SCII, they have a much more boxy shape. Despite being magnetically fired, the games still depict them as having muzzle flashes and for some reason using 8mm cartridge ammunition, despite the fact that gauss guns can do away with the cartridges by just directly launching the slugs, but StarCraft is hardly the only thing to ever inaccurately portray a gauss weapon. (Hand waved in one of the side manuals as the bullet being initially launched by gunpowder and is then accelerated through the gauss rails [sic], similar to 40k bolters with gyrojets. And they could probably hand wave the muzzle flash as a split-second of plasmized air, since the slug is traveling so fast).

Despite being one of the weakest military grade weapons, and that's an understatement given that Impaler rifles are almost at par with the laser and photon weapons commonly mounted on Terran and Protoss gunships, Impaler rifles still can pierce through about anything, and though the little holes a single Impaler leaves in enemy armor do not really bother giant humanoid battle robots, towering War of The Worlds-esque death automatons, and bone/chitin plated monsters the size of a small house, massed gauss fire could and would bring down pretty much anything just by turning it into oversized swiss cheese until it collapses under its own weight. That's why basically every Terran armed force in the galaxy worth a damn usually send marines in hundreds to drown their enemies in bodies and gauss fire. How they're able to sustain those losses on a constant basis is anyone's guess They just use brainwashed convicts drugged with steroids and adrenaline (which eventually kills them, if they somehow survive on battlefield, which they usually don't), and considering low life level anywhere outside core worlds (and even on some of core worlds), they have almost unending supply of criminals.

Although, how an infantry rifle could bring down a Terran Battlecruiser or a Protoss Carrier, which are essentially massive ships designed for large-scale ship-to-ship combat, through massed fire tends to make you wonder: What the hell?

Battletech

In the Battletech universe, Gauss Rifles are some of the most powerful solid-based weapons. Packing the power native to Heavy Autocannons, which generally suck at range, and the range and negligible heat generation usually restricted to light autocannons, which are long-ranged and produce little heat but lack the sufficient punch to threaten heavily armored 'mechs. They're capable of smashing a MadCat's cockpit off from long range with a single, well-placed shot.

The Gauss Rifle however, suffers from a few problems: they cycle rounds much slower than conventional autocannons, they have a limited ammunition count, and they're considerably heavier than most weapons. Also, while their ammunition is inert and won't explode from heat or critical hits, the weapons themselves are a bit unstable and will explode if they suffer critical hits (though for much less damage than most ammo explosions).

External Links

• A video of a real-life railgun in action. When you consider the fact that humanity is on the verge of (and certainly will) inventing a practical railgun in early M3 (which we can power effectively for naval use),the main infantry weapon of the Imperium in M41 is a shitty flashlight which, according to Dark Heresy has an effective range of 200-300 meters, the main tank armament is a 120mm smoothbore battle cannon, and the only undisputed rail weaponry the Imperium has are mainly found on its huge flying cathedrals, humanity has fallen pretty far. Or GW didn't expect humanity to progress this fast.

• Thank you Omnissiah NAVSEC for this wondrous beauty. Essentially the previous railgun, but now at a more advanced stage with a much easier and faster time to reload and fire.