The M4 MWS (Modular Weapon System) is based on the M16A4, which in itself represents a newer incarnation of the base M16A2 currently in service with forces around the globe. The M4 utilizes the strengths and internal working components of the successful automatic rifle and, along with a 1913 rail adapter system, becomes a lighter and more combat version of the weapon.
The M4 MWS is a versatile field performer with the rail adapter able to mount various compatible components including various scopes, flashlights, target designators and the M203 40mm grenade launcher. Standard ammunition is the 30-round detachable box magazine housing 30 rounds. The smaller size of the M4, when compared to the M16 series as a whole, offers up portability and increased accuracy when firing in close quarters.
As of this writing, the M4 MWS was being field tested by the United States Marine Corps and seen as a heavy-hitting replacement for select M9 9mm pistols currently in service. The thinking is that the M4 MWS would also replace the M16A4 in some cases, being fielded as a smaller, yet more potent alternative to either weapon in service, particularly for vehicle crews, airborne assault units and combat engineer elements.
Cyclic rate-of-fire is reported to be between 700-900 rounds per minute with an effective range of 500 meters to a point target and 600 meters to a target area. The front sight is adjustable and the rear site can be ranged up to 600 meters with windage taken into account. Fire selection is limited to a semi and a burst round capability along with a safety.