The M45 was able to fire a variety of projectiles in early space faring conflicts. In the early 2400s, the UNSC Marine Corps abandoned the Shotgun as their main-stay poster boy weapon. Instead it was given to less important or, depending on the situation, less visible tasks within boarding parties and police forces. The M45 never truly vanished or has been completely replaced. Eventually it found its way into the hands of the UNSC Army.
The M45 Tactical Shotgun is a special-purpose weapon used in any situation where the range of engagement is close and limited and when over-penetration is not desirable, but maximum stopping power is required. Like the M90 Close Assault Weapon System, the M45 is a pump-action, magazine-fed (dual tubular, non-detachable type) weapon that uses 8 gauge magnum (3.75”) ammunition. It features an adjustable stock, however this is purely cosmetic.
In gameplay, the M45 Tactical Shotgun is more powerful than the M90 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.
- It is possible that Bungie named this shotgun the M45 because it is the in-game counterpart to the M90 from the other games: 90/2=45.
- In the Halo: Reach Multiplayer Beta, the shotgun had cyan lights (top picture) similar to those on the M90 in Halo: Combat Evolved and Halo 3. The sights are red in the final game.
- 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 with the collapsible stock does not appear in the final version of the game.
- The M45 likely functions in a similar manner to the Ithaca M37, used in the Vietnam war, as both weapons use the same opening for both loading and ejection of shells. The M45's receiver, barrel, and magazine even resemble those of an inverted M37 with the slide placed over the barrel rather than the magazine tube. The M45 also shares the M37's ability to "slam-fire" (fire a round as soon as it is chambered)
- It is surprising that even in 2552, there isn't a semi automatic or automatic shotgun in existence. However, this could just simply be to balance out the game.
- In the Halo Anniversary Strategy Guide, the in-game shotgun is referred to as the M45E TS. It also states that it has near-identical firepower and combat ability to the M90 (the model that was originally in Halo: CE).
- The M45 appears in every Campaign mission in Halo: Reach except Tip of the Spear.
- The M45 is Emile's preferred weapon.
- The M45 is useful in multiplayer maps such as Sword Base due to the enclosed space.