From Lexicanum

The Tarantula is an automated mobile weapon system, more commonly referred to as a Sentry Gun¹. The Tarantula takes its name due to the distinctive form of its gravitic base, which allows it to traverse rough ground easily. The Sentry Gun utilises simple logic engines and is infused with the machine spirit to allow them to operate without a controller. The Tarantula is commonly found armed with twin-linked Heavy Bolter to target enemy infantry, with rapid bursts. This tactic often provides a significant deterrent to enemy assaults. A twin-linked Lascannon armed variant is also used, where the weapons are employed against enemy armour formations. Both variants are commonly used to defend forward Imperial instillations where heavier or more permanent systems are unavailable¹.

Drop Regiments such as the famous Elysian Drop Troops often use Sentry Gun equipped with Grav-chutes dropped from Valkyrie airborne assault carriers to help form defensive perimeters around captured objectives^{2 3}.

This form of weapon is utilised by the Imperial Navy, Imperial Guard, PDF , Space Marines and the forces of the inquisition.

Sources

• ¹:Imperial Armour Volume One - Imperial Guard and Imperial Navy

• ²:Imperial Armour Volume Three - The Taros Campaign

• ³:Imperial Armour Volume Four - The Anphelion Project

• ⁴:Codex Titanicus (Epic)