The Powerful, Complex Legacy of the M4 Carbine

by Kris Osborn, President, Center for Military Modernization

Over the course of many years, the US produced hundreds of thousands of battle-tested, upgraded M4A1 rifles engineered to more quickly identify, attack and destroy enemy targets with full auto-capability, consistent trigger-pull and a slightly heavier barrel.

The M4AI was the product of an extensive M4 Product Improvement Program, called PIP. PIP was a far-reaching initiative to upgrade the Army’s entire current inventory of M4 rifles into higher-tech, durable and more lethal M4A1 weapons. An Army weapons developer involved in the PIP project said “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,” an Army statement said.

The Army spent many years converting its fielded M4 carbines to M4A1 carbines; approximately 483,000, Army officials explained. “Most of the enhancements resulted from Soldier surveys conducted over time,” an Army official told Warrior. Over the years, the Army has made more than 90 performance “Engineering Change Proposals” to the M4 Carbine since its introduction.

“Improvements have been made to the trigger assembly, extractor spring, recoil buffer, barrel chamber, magazine and bolt, as well as ergonomic changes to allow Soldiers to tailor the system to meet their needs,” an Army statement said.

Today’s M4 is quite different “under the hood” than its predecessors and the upgraded M4A1 was even further refined to provide Soldiers with an even more effective and reliable weapon system, Army statements said. The M4A1 is also engineered to fire the emerging M885A1 Enhanced Performance Round, .556 ammunition designed with new, better penetrating and more lethal contours to exact more damage upon enemy targets.

“The M4A1 has improvements which take advantage of the M885A1. The round is better performing and is effective against light armor,” an Army official told Scout Warrior.