From Halopedia, the Halo wiki
The M7S Submachine Gun, sometimes referred to as the Suppressed or Silenced SMG or more colloquially by UNSC personnel as the bullet hose, black box, chum and popcorn, is a personal defense weapon issued to UNSC Armed Forces special operators.
A variant of the M7 SMG, the M7S is equipped with an external flash and SS/M 49 sound suppressor on the barrel along with an underbarrel flashlight. To assist the user in target acquisition, the weapon is fitted with a SLS/V 5B smart-linked scope. Muzzle flash is significantly reduced, and firing the weapon gives a barely noticeable sound, increasing stealth applications for the M7S Submachine Gun and increasing accuracy from decreased recoil, making the weapon more efficient at medium-long range. It fires 5×23mm M443 Caseless Full Metal Jacket from a reduced 48-round magazine. Some usage of the M7S sees the SMG employed with a laser sight.
The M7S was introduced into UNSC service in 2431, and saw use during the Insurrection. The M7S was notably employed by SPARTAN-II Blue Team during Operation: TALON, during which they captured URF leader Robert Watts. The weapon continued to see use throughout the Human-Covenant War, becoming notably iconic in the hands of Orbital Drop Shock Troopers. The weapon saw heavy use during the Battle of Mombasa in late 2552, and has since continued to see use by ODST units in the Post-Covenant War conflicts.
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