Volkite Weaponry
Volkite weapons are Martian death-rays. In Warhammer 40,000, Volkite weapons are ancient and advanced weapons based on the principle of imparting so much heat to the enemy that he literally bursts into flames inside his armour. These flaming victims then cause more damage to their own squad, as their run around screaming while emitting the temperature of a rather large and unwieldy furnace. Their main drawbacks are that they are fairly short-ranged (although not to the same extent as Melta weapons), and are somewhat less effective at piercing armor than Bolters.
They are quite literally Martian ray-guns, as only the techpriests of Mars could make them. When the Great Crusade was just starting out, there were enough to equip every single Space Marine Legionnaire with them. Sadly, as the Crusade got underway and the Primarchs were found (thus, greatly increasing the numbers of Legionnaires), demand far outstripped supply and Volkite guns were relegated to "special weapon" status. Then, with the Horus Heresy, the defection of large parts of the Mechanicum, and 10,000 years of a technological roller coaster ride, the know-how to repair them was lost and Volkite weapons gradually disappeared from the galaxy. But, hell, Games Workshop brought grav-guns back into style with the new Codex: Space Marines. Anything could happen (although that's fairly unlikely, as grav-guns were established in 40k fluff beforehand, whereas Volkite weapons were made up for 30k). Of fun note is that the new Cult Mechanicus codex still has access to a brand new one called a blaster which is about the same as a Culverin. The most similar weapon in popular fiction to Volkite Weapons is surprisingly Phasers from Star Trek. If they were turned up to the highest setting(vaporizes human targets) and had a rate of fire comparable to UZI's and ShKAS machine guns.
A note on the above, Volkite weapons were excellent assault weaponry, especially when facing massed infantry, and had more potential against light vehicles than a Bolter did, but that was pretty much their niche. Bolt weapons, which were much easier to manufacture, had a slightly longer range and marginally better armor-piercing ability, and could use numerous specialty rounds, were a better tactical weapon that could adapt to numerous situations, as well as easier to field in the numbers demanded by Legions. The main drawback in the field was that Bolters were most often fitted with standard rounds, while specialty munitions were still rare enough to only be issued to specialist squads alongside their regular bolts.
Of course, given the manner in which Volkite weapons deal damage and the effectively unimportantly small different between its armor piercing to that of boltguns, Volkite weapons would leave a heavily armored opponent vulnerable to more follow up shots due to severely weakening the target's armor. Bolters have to blow their way through with repeated shots if they fail to outright penetrate. Ultimately, Volkite weaponry is superior to bolters. Cover is useless or even a disadvantage against it, groups of enemies are excellent targets for its wielder, light armored vehicles are sufficiently vulnerable to its death ray, and heavy vehicles and powered armor would take significantly fewer shots to get through than a bolt weapon would. It is, therefore, a highly effective all purpose weapon for anti-infantry, anti-light and heavy armor, and anti-powered infantry. Its only blind spot is that it is ineffective against aircraft that do not come low enough to be in range of it.
Each weapon is named after really old real-life firearms and cannons, except the chierovile which is made-up gibberish, and the blaster which is... just a normal word? Obviously they are just picking out random words that sound "cool" when it comes to naming these things.
Volkite Weapons
A Iron Warriors Legionairre fires a Volkite Charger at a distant tank during the Battle of Tallarn during the Horus Heresy.
On the table, A Volkite weapon has good strength and decent AP, but its real power is the Deflagrate ability; any unsaved wounds suffered from a Volkite weapon each inflict another hit on the same unit at the weapon's profile (minus the Deflagrate effect; the wounds do not chain infinitely). Pretty nice.
Volkite Serpenta
The pistol of the family, highly effective and powerful sidearm but with obviously low range and rate of fire. The Adeptus Mechanicus still have a few of these on hand, but like most of the good stuff, instead of taking it apart and reverse engineering it, they instead keep most of them locked in stasis vaults and ogle them.
S5 AP5, 10" range, pistol.
Volkite Charger
The rifle of the family, as stated previously, at the outbreak of the Great Crusade were the goddamn standard weapon for the Adeptus Astartes. Which I'm sure was a terrifying prospect for the enemies of the Imperium. A Mastercrafted version is also the favoured ranged weapon of a certain Sick Fuck. Unfortunately their laborious nature of their manufacture resulted in them being relegated in favour of the Bolter, which was much easier to manufacture and supply, which was important as the crusade grew from a few thousand marines, a planet, and a moon to many hundred thousands of marines, quadrillions of Imperial Army troops, and an entire galaxy of shit to conquer.
S5 AP5 Assault 2, 15" range.
Volkite Caliver
Somewhat comparable to a light squad support weapon, longer and bulkier than the Charger, though still loaded from a box magazine and fairly easy to carry. With a better range than the Charger at a cost of being unable to fire on the move.
S6 AP5 Heavy 2, 30" range.
Volkite Blaster
The only Volkite weapon in regular plastic 40k (and not itself found in any 30k books, even the Mechanicum Red Book), and only seen on Tech-Priest Domini to boot. It might have been custom-constructed, or it might have started life as a Caliver before being integrated into someone's arm, but trades the tip of the Caliver's range for 50% more dakka.
S6 AP5 Heavy 3, 24" range.
Volkite Culverin
The heavy weapon, bulky, powerful, with a massive rate of fire and equally large ammunition requirement. It's like a heavy bolter if it fired even faster and its shots caused the enemy to spontaneously combust. Perfect for that 20 man squad of assault marines and on anti-infantry Scimitar jetbike counterparts to Meltabikes.
Heavy weapon squads full of these guys are your best option for long-range multipurpose murder, as they will incinerate entire squads of light infantry in a single salvo, and 4 shots at S6 is pretty solid against light to medium vehicles as well.
S6 AP5 Heavy 4, 45" range.
Volkite Demi-Culverin
The bigger brother to the Culverin, this is only available to the Solar Auxilla (for now). It boasts one more point of Strength and one more shot than the man-portable version, and is found on the spiffy Leman Russ Incinerator. Demi-culverin. For when you want to say "Screw that guy and everyone around that guy."
S7 AP5 Heavy 5, 45" range.
Volkite Chieorovile
Big goddamn Volkite gun mounted onto the Questoris Knight Styrix. With a range equal to the Culverin version, this baby puts out five S8 AP3 shots which is great at turning entire armies into flaming soon-to-be-corpses. Who wouldn't want to use a gun that kicks out the equivalent of 5 Krak missiles that set blobs on fire per turn?
S8 AP3 Heavy 5, 45" range.
Volkite Carronade
The biggest one of all (maybe; see above). Disgusted by the prospect of the largest weapon in a given type being able to be held by a person, those crazy Martians decided to supersize it and put it on the turret of the Fellblade super-heavy tank. At first glance it's almost comically short-ranged for a super-heavy tank weapon, but when you consider it hits absolutely everything in a straight line (which is as wide as the weapon's barrel, which is about the same as the height of a space marine) between its smoking barrel and its max range, turning entire tank columns into molten heaps of slag and reducing infantry formations into screaming, flaming soon-to-be-corpses who proceed to set their own allies alight, it ends up looking pretty good. And unlike psychic beams, the beam's strength is only reduced by other super-heavies and buildings. That said, it hits YOUR units too, so don't place anyone you don't want to lose in front of it when it fires. And don't think being inside a transport when it hits will save you; if the transport takes a penetrating hit, even if all it ends up doing is Crew Shaken, you take a bunch of hits. With the normal volkite ability to generate more. Dark Eldar, don't even bring Raiders; they'll just make it hurt more.
...although maybe they like that.
S8 AP2 Primary Weapon 1, 48" range, Haywire, Ignores Cover, and the aforementioned hits-everything rule "Heavy Beam."
In action
- A volkite charger equivalent in the game Killing Floor 2 *CHOOMING* zombies can be seen in action here.