The Rapid-Fire Battle Cannon is a variant of the Battle Cannon commonly found on Imperial armoured vehicles used by the combat walkers of the Questor Imperialis, the Imperial Knights, and by the Renegade Knights of the Questor Traitoris. These weapons are akin to a large-calibre, ballistic artillery cannon, and feature an automated loading system that allows them to fire accurate, highly-explosive shots at a rapid rate. The explosions are capable of racking up a horrific number of casualties when employed against massed infantry hordes, yet are also capable of destroying light and medium tanks with ease.
The Rapid-Fire Battle Cannon is the main ranged weapon of the Knight Paladin, but is also used by the Knight Crusader. Most Rapid-Fire Battle Cannons also feature a Heavy Stubber mounted to the weapon's gun shield, which is used to engage enemy infantry that get too close.
Due to the sheer diversity of Knight Worlds and Forge Worlds in the Imperium there exist a multitude of minor variants of the Rapid-Fire Battle Cannon, each different from the last in a number of distinct ways. All known variants include:
- Standard Rapid-Fire Battle Cannon - The most common type of Rapid-Fire Battle Cannon, this variant features a single, long-barrelled cannon and a Heavy Stubber.
- Snub-barrelled Rapid-Fire Battle Cannon - An uncommon variant, this version features a much shorter cannon barrel than the standard pattern, similar in appearance to a Demolisher Cannon. This version may or may not feature a built-in Heavy Stubber.
- Medium-barrelled Rapid-Fire Battle Cannon - An uncommon variant, this version features a shorter cannon barrel than the standard pattern. It may or may not feature a built-in Heavy Stubber.
- Upgraded Rapid-Fire Battle Cannon - A rare variant, this version possesses a muzzle break and additional hydraulic bracing, resulting in a reduction of recoil and unwanted increases in barrel height and loss of accuracy during rapid fire. This version commonly features a built-in Heavy Stubber.
- Twin-linked Rapid-Fire Battle Cannon (Side-by-Side) - A rare variant, this version features two Battle Cannons twin-linked together, in a side-by-side configuration. This version typically lacks the built-in Heavy Stubber found on the standard pattern.
- Twin-linked Rapid-Fire Battle Cannon (Over-and-Under) - A rare variant, this version features two Battle cannons twin-linked together, in an over-and-under configuration. This version typically lacks the Heavy Stubber found on the standard pattern.
- Codex: Imperial Knights (7th Edition), pp. 16, 21, 24, 29-30, 115
- Warhammer 40,000: Index - Chaos (8th Edition), pg. 109
- The Horus Heresy - Book Four: Conquest (Forge World Series) by Alan Bligh, pg. 301
- The Horus Heresy - Crusade Imperialis Army Lists, pg. 112
- Warhammer 40,000: Freeblade (Video Game)