Magnetic Acceleration Cannon

Magnetic acceleration cannon, also known as mass acceleration cannon and MAC gun, is a large coil gun fitted in most Imperial ships and serves as a ship's primary output of damage. The MAC cannon have seen various design iterations since its inception during the Golden Age of Humanity, including the legendary MARK X. Lance cannon. It is capable of tearing through heavy layers of adamantium with ease, and the heaviest variations of the MAC cannon have been noted to be able to tear a hole in a derelict Precursor ship.

Design
A MAC cannon's nature is that of a coil gun. The cannon unleashes a heavy projectile through a series of magnetic coils, increasing the payloads speed until it exits the shaft, launching the projectile at almost a fraction of lightspeed. The kinetic energy produced from such a weapon is absolutely devastating. There are a number of setbacks, however. Its lack of maneuverability is one such setback as once the payload is unloaded, it is essentially a straight line with no particular target.

Mark V Light Coil, Standard Issue
An Imperial warship is typically fitted with a standard-issue Mark V light coil cannon is capable of firing a 1000 ton adamantium projectile at 5,000 metres per second. The cannon draws power from the ship's warp core.

Series 8 Super-Heavy Coil
Colloquially referred as super MACs, these guns contain twice the power of a standard-issue Mark V light coil MAC cannon. It is often powered by a separate warp core in which it draws its energy from, allowing it to maximise efficiency. As a result, a single shot from a super MAC—travelling at an average speed of 6% of lightspeed—can crack entire continents.

Mark X Lance Cannon
Recovered by the tech-priests of the Adeptus Mechanicus during an expedition on Tython, the Mark X lance cannon is among humanity's most powerful weapons, capable of destroying entire worlds. Such a weapon requires two dedicated mini-warp cores to power its magnetic coils. The rounds used, a variant of the usual adamantium round, are fitted with a depleted uranium core; the average weightage of a round is around 1500 tons. When fired, the round travels at 13% the speed of light, producing a destructive output capable of shooting through a planet.