A standard Storm Bolter
The Storm Bolter is a double-barreled version of the standard Bolter. As it is heavier and causes more recoil than a normal Bolter, it is even more rarely used than the Bolter by the regiments of the Imperial Guard. Instead, they Storm Bolters are usually used by the Space Marine Terminators or as an Imperial main battle tank's pintle-mounted weapon. They are also used by the Grey Knights as a gauntlet-mounted weapon with its feed mounted on the rear of their armour.
Many Combi-weapon variants of the Storm Bolter exist, such as the Bolter-Flamer, Bolter-Melta, and Bolter-Plasma; these combine a Bolter with another weapon (ie. a Combi-Flamer combines a Bolter with a Flamer). While the Storm Bolter carries as much ammunition as found in stand-alone Bolters, the secondary weapon on a Combi-weapon variant of it carries only enough ammunition for a single salvo or use.
Due to its high munitions consumption, and the lack of dexterity available to the wearer of Tactical Dreadnought Armour, most Storm Bolters are fed from a large box magazine, carrying approximately 100 rounds. These rounds are identical to those fired from Bolt Pistols and Boltguns.
Before the Storm Bolter was created by the Tech-priests of the Adeptus Mechanicus, Terminators were often equipped with special Boltguns that had advanced targeting equipment and restricted firing rates. These were called Combi-Bolters. They are now only used by the Chaos Space Marines of the Traitor Legions.
Dorn's Arrow
Chapter Master Pedro Kantor of the Crimson Fists Space Marines uses a unique Chapter relic Storm Bolter known as Dorn's Arrow. The firing rate of this Storm Bolter is astounding: it is able to fire upwards of 300 rounds in just a few seconds. Because of this, Kantor uses a back-mounted ammuntion source, feeding the weapon using ammunition belts that feed into either side of the weapon. Dorn's Arrow is mounted on Kantor's wrist, allowing him to freely use both hands while still keeping his weapon ready to fire.
Sources
- Warhammer 40,000: Wargear (2nd Edition)
- Warhammer 40,000: Wargear (4th Edition)