From Halopedia, the Halo wiki
The M6G PDWS is a semi-automatic, recoil-operated, magazine-fed, large-caliber handgun. It is a later model of the M6 series sidearms that was distributed to officers and vehicle/weapon crews. The weapon has a polymer handle, along with a titanium alloy body and a nickel-plate finish. The sidearm fires the M225 SAP-HE (Semi-Armor Piercing, High Explosive) rounds from an 8-round magazine at a velocity of 427 m/sec (1302.35 ft/sec). In addition, the weapon can be issued with a KFA-2 x2 optical, smart-linked scope.
The weapon's performance seems tied to its year of manufacture. Whereas the 2546 model used by the UNSC Army has a rate of fire of 240 rounds per minute (4 rounds per second), the 2552 model used by the UNSC Marine Corps fires at a rate of only 120 rounds per minute (2 per second). In either case, with a maximum effective range of 50 meters, superb accuracy, and high stopping power, the M6G proves very useful during scenarios where primary arms are not available.
The M6G uses 12.7×40mm M225 SAP-HE (Semi-Armor Piercing, High Explosive) .50 caliber ammunition 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. Probable reasons for using semi-armor piercing rounds instead of armor piercing projectiles are both to prevent over-penetration of hostiles and decreasing the risk of friendly fire during CQB and urban combat, and their devastating efficacy against soft targets. The explosive properties of the rounds render them decently effective against personal shielding systems and are also capable of damaging lightly-armored vehicles.
Although M225 SAPHE ammunition is standard issue for the M6 PDWS, there are more “exotic” ammunition types available to UNSC personnel only by Mission Conditional Requisition (MCR).
2546 model - M6G
This model was issued to UNSC Army troopers on Reach during the Covenant's invasion in the summer of 2552. It has a rate of fire of approximately 240 rounds per minute (4 rounds per second), though its accuracy suffers slightly as a result. The slide is tapered at the rear and sports forward-facing, diagonal serrations. The magazine release is set above and parallel to the lower lip of the trigger; the magazine's lip is shaped like an irregular trapezoid. The striker juts farther from the slide, reminiscent of a hammer. This model is equipped with an underslung flashlight attachment or laser module.
2552 modification package - M6G2
By 2552, a modification package of the then latest revision of the M6 pistol series was released. Referred to as the M6G2, this version of the M6 was used by UNSC Marines stationed on Earth during the fall of 2552. It sports the same general design and proportions as the aforementioned version, despite a subtly longer barrel and lack of an underslung attachment. While its rate of fire is only half that of its predecessor, (roughly 120 rounds per minute), its accuracy is superior. The top attachment plate's mounting pins are closer to the muzzle. The slide has vertical serrations and a flat rear. The magazine release is set just in front of the safety switch and has a thin, rectangular lip akin to earlier M6 models. The striker is recessed into the slide as on a 21st-century Glock. The 2552 model was later recorded in Machines, Materiel and Munitions from the Human-Covenant Conflict, 2525 - Present.
Changes from Halo 3 to Halo: Reach
Non-canon and dubious canon appearances
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