Radium Weaponry
Radium Weapons sometimes called Rad Weapons are deadly and highly dangerous weapons that are used exclusively by the forces of the Skitarii Legions of the Adeptus Mechanicus. Think of them as nuclear rifles. Radium Weapons are so volatile that they eventually kill their wielders. Although quite frankly, having a gun that just ends up killing you seems to venture more into Grimderp territory more then anything else. Their baroque beauty belies a singularly vile function; not only to strike, but to render the battlefield as deadly as the rad-wastes of Mars. Each weapon's bullet cylinder is so thoroughly bathed in radium that a volley can cause a localized rad-storm. Those inside such a storm soon find their flesh blackening and sloughing away.
On tabletop, generally speaking, Rad Weapons have a low strength of 3 as basic, but a to-wound of 6 causes two (instead of one) auto-wounds which must be saved separately. Mathammer-wise this means when it fired en masse it deals exactly as much damage as your standard S4 AP5 guns against anything but T6 and T7, against which it's twice as good. "Auto-Wounds" means it can wound even if the enemy's Toughness should be too high, which is nice for piling the saves on big wraith constructs and Iron Arm-protected daemons.
Variants
There are three types of Rad Weapons.
Radium Pistol
A small pistol that uses scaled down radium technology, usually used by Skitarii Vanguard and Ranger Alphas. These nuclear armed hand cannons are unfortunately not as rad (Hah! See what I did there?) as one might think. You're better off ponying up the points for the Phospher Blast Pistol instead, unless you *have* to have radium. The PBP costs the same and is more generally useful.
Still, it is quite capable at getting the job done when absolutely needed.
Radium Carbine
A rapid firing weapon capable of a punishing rate of fire, it is the main armament of Skitarii Vanguard. If you want to roleplay as Fallout in WH40K, this is the gun for you. On the table, at 18" range and Assault 3, the Radium Carbine usually means lots of hits at short-mid range with the potential of cascading effect when they start causing additional wounds later.
The basic weapon of the Skitarii Vanguard as mentioned before. With 10-man vanguard units, this weapon causes so much wounds that can potentially delete a squad or even a MC.
Radium Jezzail
A motherfucking nuclear sniper rifle. The Radium Jezzail is a long sniper-like weapon that is sometimes used by Sydonian Dragoons instead of a Taser Lance. On the table, it's a two shot sniper version as a weapon choice for the Dragoon, in place of its Taser Lance, for free. To Wound of 6's cause two AP2 wounds instead of 1 which, we will remind you, you get to allocate if you also get a 6 on your To Hit.
Basically, if you're going to be taking these on Dragoons, you will have to commit to it; as in they're all gonna be sniping. By and by, pretty good for close range heavy infantry/monstrous creature sniping. Could be fun against Riptides with a little luck.
Irradiation Projector
An Irradiation Projector, also known as a Rad-Cleanser or Irad-Cleanser, are specialized Adeptus Mechanicus weapons. A potent anti-infantry relic of the Dark Age of Technology, the weapon itself is a dish-like projector connected to a bulky generator which unleashes a powerful blast of cross-spectrum radiation.
Victims caught in the blast suffer horrendous deaths as they are boiled alive from within and blasted apart on a cellular level. Though less effective against vehicles or targets with heavy armor, the target will likely die later from radioactive contamination.
The biggest users are Thallaxes whose enclosed cybernetic harness means that they are less susceptible to radiation poisoning.