The M6D in particular is an "up-sized" version created for use by SPARTANs, and can be integrated with a reticule projected into the HUD of the MJOLNIR Powered Assault Armor/Mark V, as well as being used as an officer's model.

In Halo: Combat Evolved, Master Chief first obtains the M6D Pistol from Captain Keyes right before he crashes the Pillar of Autumn starship into the megastructure known as Installation 04.

[1] The M6D Pistol's unusually high power was rumored to have been caused by a last-minute change in the game's code by Bungie co-founder Jason Jones that secretly increased the weapon's damage range.

[2] Jones stated that he would "take the credit and blame for the pistol in Halo", calling the tweak due to his attention to smaller details.

[8] Jason Johnson of Kill Screen called the M6D "the most infamous video game weapon of them all", describing it as a "one-holy piece of weaponry" but criticizing its decrease in power after the original Halo, saying it was "reinvented as common trash".