The Meltagun, also called a "Fusion Gun," "Melter," or "Cooker," is a powerful, short-ranged anti-armour weapon that produces an intense, energetic beam of heat in the thousands of degrees Centigrade. However due to their weight, short range of around 10 meters and it's difficulty of production, the Meltagun is mainly used by Stormtrooper squads as a mobile anti-vehicle weapon. Cutting through tank armour like a hot knife through butter, the Melta-Blast then instantly incinerates the crew of the unfortunate vehicle.

Meltaguns emit devastatingly intense but short-ranged blasts of heat which can melt through almost any material by inducing highly pressurised gases from an ammunition canister into an unstable sub-molecular state which produces nuclear fusion and directing the resulting energies down the barrel. Melta Weapon usage is always accompanied by a distinctive hissing sound as the Melta beam boils away the water in the air, then a roaring blast as the beam reduces the target to charred scraps or molten slag. Meltaguns are the premier Lenehenese anti-armour weapons, and few if any vehicles can withstand their power. God help any infantry caught in the blast, as any organic target would be boiled alive in their own body armour.

A smaller more compact version of the Meltagun exists for use, although due to it's incredible difficulty of production it is only available to high-ranking officers of the Imperial Guard and Adeptus Custodes.