Shotgun

Summary
The M90 shotgun is a pump-action magazine-fed (dual tubular non-detachable type) weapon. It fires 8 gauge magnum (3.5") rounds. This weapon is very effective against targets at close range and may be used to engage several targets simultaneously at medium and long range.

A weapon that has barely changed since it was first conceived, the Shotgun is a close-range firearm that can stop any creature, Human, Flood or Covenant in its tracks. Deadly at short distances, it is a weapon that even Elites should fear: it can overload some shields in a single shot. With it, you can make aggressive charges towards foes, punching through flesh and armor before they have the opportunity to return fire. It can also be, in turn, a great means of defense. When pinned down under cover - or having ducked behind a corner to allow the Master Chief's shields time to recharge - any Covenant soldier with the tenacity to rush your position should meet with a venomous rebuke from your M90. The range of the Shotgun has been slightly diminished for Halo 2.

Alas, due to the high spread of its projectiles, the Shotgun is practically useless over medium and long distances. It should always be complemented by a secondary weapon that addresses this most salient of weaknesses. Additionally, the M90 is reloaded one cartridge at a time. During furious combat exchanges, it will feel as if you could grow a beard in the time it takes to load it up - and that's just for female Halo 2 players. Every opportunity that you get, hide and perform a manual reload. Note that you can interrupt the process of loading the Shotgun by firing or melee attacking at any time. You can then, as you might expect, use the remaining cartridges.

The UNSC was not the only one using Shotguns: in the later levels, some Brutes and Flood Combat Forms use Shotguns too.

Multiplayer Tactics
First, the most important time you should worry about shotguns is when you see someone in the sights of your dual wielding combination, blinding rushing towards you with a black stick in his hands. With a sudden boom, you are on the floor, one added to his Skill score. This is the shotgun. Second deadliest weapon at short range. The second important thing to remember is to not show this weapon off. The distinct sound can be heard over short distances.

To avoid revealing the weapon, you should primary use it as a back up until you see someone close. This is a great weapon to use to camp with. You can use this when guarding many key spots: Tunnel to base in Burial Mounds, The Top areas in Lockout, quickly running around the dish in Ascension (running to avoid drawing sniper fire and others), and so on and so forth. As long as you can find a spot where there's one way out and lots of ways to come in, you're as sound as a pound.

Another important part of Shotgun tactics, is to know when to pull the right trigger. Many times I've pulled first, only to have someone run right up to me, and have a clean shot. You need to know exactly the range between the shotgun and his head to make a killing blow, and you'll have mastered the shotgun.

Lastly, always reload the Shotgun after you fire, it will save you time and health in the long run because fully reloading the shotgun takes a whopping 7 seconds.

Technical Data
Official Designation   : M90 Shotgun Projectile Type        : 8-Gauge Magnum (3.5")  Dual-Wield              : No  Damage                  : High  Range                   : Very Close (Halo 2) Medium (Halo 1)  Accuracy                : Low  Rate Of Fire            : Low  Autofire Capability     : Manual  Magazine Capacity       : 12 Bullets  Ammunition (Additional) : 36 (3 Magazines) {Was 60 (5 magazines) In Halo: Combat Evolved}  Reload Speed            : Very Slow  Melee Attack            : Fast  Scope                   : No