M45 shotgun

The M45 TS Close Assault Weapon System is a shotgun used by the United Nations Space Command.

Design Details
Much like any other shotgun, the M45 TS is a special-purpose weapon used in any situation where the range of engagement is limited, over-penetration is not desirable, but maximum stopping power is required.

Trivia

 * The M45 TS will presumably be more powerful than the M90 Close Assault Weapon System in Halo 3 since Bungie has stated in a Game Informer interview that the rounds will now be packed closer when fired and the range has been improved as well. The ammo capacity from the Halo 3 version has been kept.
 * When the weapon's pump is slid back, the loading port opens with it. Also, the shell is ejected from the same location it is inserted, the top.
 * It is possible the 'TS' in the name stands for Tactical Shotgun, making the official designation of the weapon the M45 Tactical Shotgun.