The powerful Lascannon is a formidable laser weapon whose energetic shot is capable of penetrating most armoured vehicles. It is the favorite anti-tank weapon of the Imperial Guard and is also commonly used by the Space Marines. Its high strength and armour-piercing ability make it a formidable weapon and when it is twin-linked, it becomes even more deadly. However, it is very heavy and power-consuming, and must recharge after every shot, making it a poor anti-personnel weapon. As a result, it is usually installed on tanks or Sentinel platforms, and in the Imperial Guard, two-man teams are required to operate and carry around a single Lascannon. To accommodate the increased power output, the Lascannon has become the largest man-portable form of Las-weaponry, the barrel being several times larger in diameter and length than the standard Lasgun. Space Marines also make extensive use of the Lascannon; it is used by Devastator heavy weapon squads, Dreadnoughts, Predator Annihilators, and Land Raiders. The primary difference between a Lasgun and a Lascannon is the size of the weapons. While the Lasgun is easily handled by a single Guardsman, the Lascannon requires a special housing of such weight and bulk that it requires a two-man team to maintain and fire it. Due to their genetically-enhanced strength, individual Space Marines may carry Lascannons whose power sources have been integrated into their Power Armour.
Each Lascannon charge pack is good for only one shot before it must be replaced. This means it has a slow rate of fire due to the need to change the pack after each shot, and the packs cannot be recharged like those of a Lasgun. The power of the Lascannon's fire means that the barrel is damaged quickly by the energy discharge but can easily be changed, much like the Lasgun. Lascannons are very reliable as the technology has been perfected by the Imperium over many millennia rather than scrounged from a newly rediscovered and imperfectly understood Standard Template Construct. As such, they are the preferred weapon type by many Imperial Commanders because the reliability of a weapon is most important when in combat.
Lascannons, due to their high strength and reliability, are often mounted on Imperial Guard or certain Space Marine tanks. When used as a vehicle weapon Lascannons are often twin-linked to improve their accuracy. Many tanks can have sponson or hull-mounted Lascannons to provide them with a secondary weapon to their primary turret in case it is damaged. Lascannons are a common sight amongst the regiments of the Imperial Guard, but less so in the ranks of the Space Marines, who rely more on Melta Weapons.
The Lascannon works in much the same way as the Lasgun, albeit with significant differences in practical operation that derive from the massive increase in power output. The Lascannon's beam produces a myriad of energetic side effects, including significant muzzle flash, more rarely seen in standard Lasguns, owing to the correspondingly greater power put into the laser emitter and consequent increase in plasma blooming. The beam is also incredibly brilliant, being purple or white in color; this is due primarily to the increase in higher-energy plasma in the air. It should be noted that some Chaos Lascannons have been observed to fire blue-tinged bolts, which could be a combination of their age (most Chaos Lascannons date from before the Horus Heresy, and are therefore slightly less technologically advanced) and wear and tear from thousands of years away from Imperial maintenance facilities, both of which would result in a beam of slightly lower energy output and the resulting change in the colour of the beam in the visible light spectrum. Lastly, and perhaps most tactically significant, Lascannons require a far longer charging/cooldown time than Lasguns, which relegates them to an anti-vehicular role in most armies.
Lascannons are a part of the arsenal of many Imperial and Chaos armies, more so than the Lasgun; many armies physically capable of withstanding the recoil of solid-slug anti-infantry weapons comparable to Lasguns (Space Marines, Chaos Space Marines, etc.) still use the Lascannon as vehicle-mounted anti-armour weaponry, relying on its inherent accuracy and the lack of its need for ammunition, when compared to a missile system of equivalent damage. The Imperial Guard, which employs laser technology to a much greater degree than the Astartes, uses Lascannons to arm vehicles that do not need heavy cannons, like Sentinels.
- Warhammer 40,000 Rulebook (3rd Edition)
- Warhammer 40,000 Rulebook (4th Edition)
- Imperial Armour Volume Five - The Siege of Vraks - Part One
- Imperial Armour Volume Six - The Siege of Vraks - Part Two