The M4/M4A1 5.56mm Carbine is a lightweight, gas operated, air cooled, magazine fed, selective rate, shoulder fired weapon with a collapsible stock. It is now the standard issue firearm for most units in the U.S. military.
Equipped with a shorter barrel, collapsible stock and detachable carrying handle (with a built-in accessory rail) it provides soldiers operating in close quarters with improved handling and the capability to rapidly and accurately engage targets at extended range, day or night.
A shortened variant of the M16A2 rifle, the M4 carbine provides the individual soldier operating in close quarters the capability to engage targets at extended range with accurate, lethal fire. The M4-series Carbine achieves over 80% commonality with the M16A2 Rifle and replaces all M3 .45 caliber submachine guns, and selected M9 pistols and M16 rifles.
The Army is pursuing a two-phase PIP to keep the M4 carbine inventory strong. Phase I upgrades the Army’s M4s to the Special Forces’ M4A1, while Phase II explores future improvements for the M4A1 Carbine to deliver enhanced reliability, durability, ergonomics and zero retention.
There are several benefits to upgrading M4s to M4A1s. Compared to the M4 , the M4A1 has full auto capability, a consistent trigger pull, and a slightly heavier barrel. The heavier barrel is more durable and has greater capacity to maintain accuracy and zero while withstanding the heat produced by high volumes of fire. New and upgraded M4A1s will also receive ambidextrous fire control.
Project Manager Soldier Weapons (PM SW) initiated Phase I by modifying its contract for the production of M4s to the M4A1. PM SW took delivery of 9,582 new M4A1s to complete this action. In support, TACOM Life Cycle Management Command will have fielded approximately 6,000 M4A1 Carbines to the 101st Airborne Division by September and plans to field an additional 3,000 M4A1s to another unit within the next several months.
