M4 Deck Gun

The M4 Deck Gun is a type of weapon utilized by lesser tonnage UNSC warships. First developed in 2576, it was a successor to the M3 Deck Gun, used from 2548 through 2576, and the M2, which was used from 2518 to 2552 on some warships that didn't have the time (or resources) to receive the refit. The weapon plays multiple roles though the most prominent is as a support weapon to destroy lighter enemy warships. Other roles of the M4 include anti-fighter, orbital bombardment. Depending on length of the barrel, the M4 can do anything ranging from destroying fighters to penetrating up to 47 centimeters of Titanium-A armor with a standard 25-ton slug.

Standard
The standard slug of the M4 is a Ferric Tungsten projectile, much like that of the M4's larger cousins - the Magnetic Accelerator Cannons.

Penetrator
The penetrator round is an extremely sharp projectile with a super durable tip for penetrating ships' hulls and exposing its interior to decompression.

Carpet
The "carpet" round is not a single round, but actually two dozen pellets in a metal shell. A small charge in the projectile will detonate after a set time. The pellets will scatter, producing a carpet effect. These are especially useful for precision carpet bombings and when attacking thin-hulled, large vessels.