The M4 Carbine series offers lightness, speed, mobility and firepower. It is standard issue for brigade combat teams in theater. The system is one pound lighter and more portable than the M16 series of rifles. The M4 series of carbines can also mount with the M203A2 Grenade Launcher, M320A1 Grenade Launcher or M26 Modular Accessory Shotgun System.
In September 2010, Headquarters Department of the Army authorized the M4A1 as the standard carbine for the U.S. Army. Compared to the M4, the M4A1 is fully automatic, incorporates a new ambidextrous fire control, and utilizes a heavier barrel that increases the weapon’s capacity to withstand heat produced by high volumes of fire. The improvement plan for the M4 is broken into two phases. As part of Phase I, PM Soldier Weapons converted its contract for all remaining M4s to M4A1 specifications. Subsequently, PM Soldier Weapons initiated a competition for an additional 24,000 M4A1 Carbines to complete its acquisition objective. It issued solicitations for weapon components to convert fielded M4s into M4A1s with ambidextrous fire control assemblies through Modification Work Orders beginning in summer 2013. Phase II explores the feasibility of further improvements to the M4A1. In one solicitation, the Army concluded no bolt and bolt carrier assembly submissions outperformed the M4’s current assembly, particularly in the areas of reliability, durability and high-temp/low-temp tests. The Army continues to compete and test forward rail assemblies.
The M4 Adapter Rail System (ARS) replaces the hand guards, allowing a Soldier with M4/M4A1 Carbines additional MIL-STD-1913 rails to attach mission-specific accessories to enhance lethality and Soldier effectiveness. Soldiers can add or remove accessories such as the laser rangefinder, infrared illuminator/pointer, and thermal sights as the mission dictates without the use of special tools.