The heavy bolter is the bolter's larger, hungrier cousin — a belt-fed support weapon that vomits a torrent of fist-sized, mass-reactive shells downrange. Each round is a self-propelled rocket that detonates inside its target, and fired in a stream they turn massed infantry into red mist and shred light vehicles to scrap in seconds.
Where the boltgun is a rifle, the heavy bolter is a wall of explosive fire, its deep hammering roar rolling across the battlefield as spent casings cascade from the breech. Its recoil is savage, so it is braced on bipods, bolted into vehicle mounts, or shouldered by transhuman warriors and servitors who can absorb the punishment of sustained fire without being thrown from their feet.
It anchors the heavy squads of the Space Marines and the fire-support platoons of the Astra Militarum, and bristles from the sponsons of tanks and the walls of countless Imperial bastions. Wherever a line must hold against a tide of bodies — a horde of cultists, a swarm of xenos, a mass of charging infantry — the heavy bolter is there to reap them, its thunderous rhythm the sound of an assault being drowned in its own dead. Gunners speak of it with a rough affection, for it rewards a steady nerve and a firm grip, and a crew that keeps its belts fed and its barrel true can hold a breach against odds that ought by every reckoning to sweep them away.