The autocannon is a heavy automatic weapon that fires large, high-velocity explosive shells in rapid succession, bridging the gap between anti-infantry firepower and dedicated anti-armour weapons. Each round is far larger than a rifle bullet, and a sustained burst can punch through light and medium armour, tear apart massed troops, and bring down flying targets. Its distinctive hammering report is one of the most common sounds of pitched battle in the 41st millennium.
Rugged, versatile, and comparatively simple to manufacture and maintain, the autocannon is fielded by countless factions. The Astra Militarum mount them in heavy weapons teams and on vehicles, the Space Marines carry them into battle aboard walkers and tanks, and even the ramshackle war machines of the Orks bristle with crude, oversized copies. This ubiquity owes much to the weapon's balance of range, power, and reliability.
Autocannons come in an enormous variety of patterns, from twin-linked anti-aircraft mounts to the sponson guns of armoured vehicles. They fire a range of specialised ammunition, allowing crews to switch between shredding infantry and cracking open transports. Neither as delicate as an energy weapon nor as short-ranged as a melta, the autocannon endures as a dependable workhorse of galactic warfare.