M45 shotgun

The M45 Tactical Shotgun, formally known as the Tactical Shotgun, 8 Gauge, Pump Action, M45, is a shotgun used by the UNSC Defense Force. It is manufactured by Misriah Armory and is commonly used alongside the M90 Close Assault Weapon System, a functionally identical copy designed by Weapon System Technologies.

Overview
The M45 is used during most close-combat scenarios, particularly in urban areas with heavy enemy occupation. It was used in numerous MOUT situations during the Insurrection and was met with widespread acclaim by its users. The M45 later saw widespread use during the Human-Covenant War.

Design details
The M45 Tactical Shotgun is a special-purpose weapon used in any situation where the range of engagement is limited and when over-penetration is not desirable, but maximum stopping power is required. The M45 is a pump-action, magazine-fed (dual tubular, non-detachable type) weapon that uses 8 gauge magnum (3.75”) ammunition. The standard M45 features a six-round magazine, though the M45E features a twelve-round magazine. The M45's factory-default sights are colored red.

M45D Tactical Shotgun
The M45D is a variant of the standard M45 Tactical Shotgun, and is one of the many weapons brought aboard the after the Human-Covenant War.

M45E Tactical Shotgun
The M45E is a variant of the standard M45 Tactical Shotgun. The E variant boasts greater stopping power than the standard M45 and has a twelve-round internal magazine rather than the standard model's six-round magazine. It features blue iron sights instead of the red sights common to the original model.

DTM Series
Due to the M45's popularity among UNSCDF service members during the Insurrection, Weapon System Technologies opted to design a more affordable and more practical copy of the M45; the resulting M90 Close Assault Weapon System is part of the DTM Series, which is marketed to the military, law enforcement, and civilians. The standard model of the M90 Close Assault Weapon System is functionally identical to the M45E, possessing a twelve-shell internal magazine, as well as matching the original in range, shot spread, and stopping power. The M90A is based on the original M45 Tactical Shotgun and performs almost identically, despite its longer barrel; it too features a six-round internal magazine. Although the M90 has since dominated both the military and private sector, it is common for UNSCDF personnel, particularly Marines, to use both weapons concurrently.

Halo: Reach
In gameplay, the M45 Tactical Shotgun is more powerful than the M90A Close Assault Weapon System from Halo 3 and Halo 3: ODST. The pellets have a tighter grouping and the range is superior as well, which also makes it harder to hit multiple enemies at close range. Although this change is hardly noticeable, impact force can be noticed as damage is higher.

The shotgun is very powerful in small confined maps. It should be used as a "corridor sweeper" because of its extreme damage at close range. When you are carrying this weapon people will mark you out as an important target due to the fact that you control a power weapon. In Halo: Reach it has more recoil than in Halo 3 where it has less recoil.

Halo: Combat Evolved Anniversary
In Halo: Combat Evolved Anniversary, the M45E is used in lieu of the M90 CAWS featured in the original game. As the changes between the original weapon and its replacement are superficial, the weapon performs identically to the M90 in Halo: Combat Evolved.

Halo 4
The M45D Shotgun, according to 343 industries employee Chris King, has "a lot longer range now, less damage falloff, and is quite a bit more powerful than say the Reach version overall." In terms of relative firepower, the shotgun is a one-shot kill weapon and should be used for close encounters. It is notable for penetrating enemy shields, particularly Elites, and it takes only two shots to kill a Promethean Knight.

Trivia

 * It is possible that Bungie named this shotgun the M45 because it is the in-game counterpart to the M90 from the other games: 45 is half of 90.
 * In the Halo: Reach Multiplayer Beta, the shotgun had cyan lights similar to those on the M90. The sights are red in the final game.
 * In Halo: Reach, the M45 is pumped at the end of every reload animation; similarly, when a Sangheili character draws this weapon, they cycle the action. In reality, doing this when the weapon's chamber is not empty would eject an unused shell.
 * In the Halo: Reach strategy guide, the silhouette used to mark shotgun spawns points on multiplayer maps appears to be missing their stocks. However, the M45 does not feature a collapsible stock and does not appear in the final version of the game.
 * In the second issue of Halo: Fall of Reach - Boot Camp, the captain of the retrieves several shotguns from a cryo chamber. In the first two panels, the shotguns appear to be M45s, though they appear to be M90s in subsequent panels.

List of appearances

 * Halo: Reach
 * Halo: Fall of Reach
 * Boot Camp
 * Halo: Combat Evolved Anniversary
 * Halo 4