The M6D Pistol is an up-sized UNSC handgun issued to Navy officers. This model has been upscaled for use by SPARTAN-IIs in MJOLNIR armor. Even though the Spartan issue pistols are larger than the standard-issue variants (~117%) they can still share magazines. The M6D is a semi-automatic, recoil-operated, magazine-fed, large-bore handgun that is controllable even during rapid fire, although at the cost of accuracy.
In-game, the player can hold the trigger down, and the weapon will fire repeatedly without additional pulls of the trigger.
Operators can achieve an effective rate of fire of 3.5 rounds/sec or 210 rounds/min. The weapon is very accurate out to its maximum effective range. This accuracy allows incredibly precise target engagement at long range. This, combined with its decent damage against Energy Shields, makes it a viable option when faced with shielded opponents, such as Elites. It is, however, even more effective against unshielded infantry targets, being able to kill most targets in one shot to the head or two to three shots to the body.
The M6D is a semi-automatic weapon - this principle of weapon operations means that the weapon will cock itself after every shot due to recoil and will continue to do so with every trigger pull until the magazine is empty. The M6D also uses the short recoil principle; it uses the force of the recoil to eject the spent casing, chamber another cartridge, and re-cock the weapon so that it may be fired again.
Before the first round can be fired however, a round must be chambered. This is done by inserting a loaded magazine into the grip of the weapon, and then by pulling the slide back completely and letting it slingshot forward, which takes a round from the top of the magazine and carries it into the chamber.
To reload, the empty magazine must be removed with the magazine release button located on the grip and a fresh magazine inserted. Once the fresh magazine is inserted, the slide is allowed to return to its normal position by the operator. There is no need to re-cock the weapon. Cocking is only necessary when chambering the first round when bringing the weapon out of "safe" mode - safety on, uncocked, and unloaded.
The M6D is a very basic pistol compared to most 26th century technology. It is a large handgun, having an overall length of 26.7 cm and possesses a rifled barrel, improving accuracy by spinning the bullet. It is issued in a hard chrome finish color and operates like most contemporary pistols. It has rear sights but it does not have a forward sight blade, which is replaced by the smart-link scope. It features a KFA-2 2x optical, smart-linked scope. This scope links directly to a user's HUD or a Marine eye piece. It also has a large grip guard, which helps prevent the user from dropping it and a chrome barrel which helps prevent corrosion.
The M6D uses 12.7x40mm M225 SAPHE (Semi Armor Piercing High Explosive) magnum loads. These rounds have a jacket of copper or cupro-nickel around the projectile while the projectile itself is hollow and filled with an explosive compound and a delayed-detonation impact fuse. When the round impacts a target, the jacket will initially help the projectile maintain its shape, allowing it to travel into the target before detonating almost immediately after impact, causing massive tissue damage and system shock.
Semi-armor piercing rounds are more effective against infantry targets as compared to armor piercing rounds due to the massive KE dump and catastrophic system damage caused by internally-fracturing rounds, and have the added bonus of posing less risk to friendlies and noncombatants in the vicinity of the target. The explosive properties of the rounds also render them decently effective against personal shielding systems and are capable of damaging lightly-armored vehicles.
The M6D PDWS is one of the UNSC's most trusted combat pistols. It is very accurate, allowing for successful engagement at any range below 122.7 meters. It also does a considerable amount of damage against both shielded infantry and flesh, as it fires 12.7x40mm M225 SAP-HE rounds. The large bullet and cartridge size yields a large amount of kinetic energy, enough to quickly deplete any form of energy shields.
Its semi-armor-piercing ability, combined with the high kinetic energy allows the bullet to penetrate most physical armor, after which its high explosive core detonates. This means it is capable of killing an Unggoy in one shot and a Sangheili in 5 shots on average, 3 to down the shields and 2 to finish it off. In multiplayer it can deplete a player's shield in 3 shots, and if the last shot hits the opponent in the head, kills them.
Although the M6D has many advantages, the weapon does have a few weaknesses. A person using the M6D must be a good marksman, to compensate for recoil on follow up shots. The pistol can hit a target at long ranges; however it cannot kill or even impact a target at a distance greater than 122.7 meters. Although at those distances a sidearm should not be used unless in an emergency.
- If you are new or rusty to using the M6D in Halo: Combat Evolved, the best tactic to use against Elites is to first hit them with short bursts (or full auto at close range) from the MA5B ICWS Assault rifle then switch to the pistol for the final blow. This not only saves ammo but reduces the risk of having to switch out the weapon for another.
- Using the Plasma Pistol and M6D against Jackals and Elites is another great way to save ammo. This combo, commonly known as the Noob Combo, can be used at all ranges, as long as the Plasma Pistol (especially in its overcharged state) can reach the enemy. This combination serves the player well in all difficulties, especially on Legendary.
- When facing Jackals, fire off a few shots on the Jackal's shield, the Jackal will duck and roll allowing you to get off either a critical headshot or to disorient the Jackal for the kill.
- When firing at shielded Elites, it's easy to tell whether you got a headshot or not, as they will jerk their head far backwards when it's a headshot.
- If you can shoot Hunters in their exposed back with an M6D, they will instantly die with one shot, even on Legendary. The same will happen if you manage to get them in their exposed fronts. This is easily achieved by getting the Hunter to charge you, while back-pedaling furiously, letting it swing at you (exposing its front) and popping one round into it at point-blank range. Or, as it swings its shield, simply sidestep around the attack and fire point blank into its exposed back.
- A well placed shot to the opening on the chest of a Flood Combat Form can instant kill it.
In Multiplayer, players use the M6D as the weapon for any situation. In the PC version of the game, it is the best all-around weapon, except in situations requiring vehicle killing or CQB power. It is capable of killing a fully shielded player in three shots to the head. The pistol also cuts down the usual strife that surrounds sniper rifles; a player won't necessarily kill their teammates for the S2-AM when they have a mid-range weapon with a scope.
- When getting into a Pistol battle remember the tried and true strafing tactic; it is harder for an enemy player to hit you.
- Remember that the M6D shots do not travel instantly; keep this in mind at when fighting at longer ranges.
- Using the M6D to pull off the Double Melee glitch is very effective when an enemy player is too close to you. Remember though that unlike the BXR glitch in Halo 2 there is a disadvantage, in the form of a possible misplaced grenade.
- It was mentioned during an episode of the Bungie Podcast that there was an internal debate about how powerful the M6D should have been. It was stated that the weapon was supposed to be weaker, but an employee made a last-minute code change that gave the pistol its power.
- In a July 2013 interview, Jason Jones was quoted as having said, "I added code specifically, when the map was loaded, to change a single number on the pistol." This was to increase the damage to what it was at release, and later saying, "I will take the credit and blame for the pistol in Halo."
- The M6D has Chinese character/Japanese Kanji for seven written on it.
- In the Halo 2 multiplayer map Tombstone, there is a M6D pistol crate that's behind the right side of the fence that is stretched over the water trench in the middle of the map. You must zoom in to see it properly.
- The Magnum in Halo: Reach (the M6G), after the 2011 title update, has the same characteristics as M6D including the three-shot kill in the new playlists. However, any game that was not affected by the TU still has the 5 shot kill pistol. The magazine size was not modified.
- In "The Sprint", the M6D is shown in several clips and is mentioned being a Legendary Weapon in Halo 5: Guardians.