The M4 Deck Gun was a type of Gauss weapon employed by capital and escort-grade space-faring combat vessels of the United Nations Space CommandNavy. First developed in 2572, it was a successor to the M3 Deck Gun, used from 2548 through 2576, and the M2, which was used from 2518 through 2552.
The weapon plays multiple roles though the most prominent is as a support weapon to destroy lighter enemy warships. Other roles of the Model 4 include anti-fighter, orbital bombardment, and suppressive force applications, among others.
Standard - A ferric tungsten projectile, much like that of the M4's larger cousins - the Magnetic Accelerator Cannons. It was by far the most popular variety of ammunition to be used with the Model 4.
Penetrator - An extremely sharp projectile with a super hardened tip for cleanly penetrating ships' hulls and exposing its interior to decompression. These were largely unpopular because of their nemesis: the airtight bulkhead.
Carpet - Not a single round, but actually two dozen flechette-like darts in a composite shell. A small charge in the projectile will detonate after a set time. The pellets will subsequently scatter, producing a carpet effect. These are especially useful for precision carpet bombings and when attacking thin-hulled, large vessels such as those often used by larger insurgent cells.