The M231 Firing Port Weapon

America’s Longest War

The Cold War was the gift that kept on giving. I tasted a bit of that while in uniform myself. I have read if we took everything we spent on defense from the end of World War II until the fall of the Iron Curtain, we could raze and rebuild every manmade structure in North America. That’s honestly pretty pathetic. However, the Cold War did see some simply extraordinary technological advancements.

The tactical tit-for-tat went on for decades. We built the XB70 strategic bomber, and the Russians designed the MiG-31 interceptor to counter it. When we canceled the XB70 after a catastrophic in-flight disaster, the Russians sure felt stupid but they are still using those geriatric MiG-31’s in the skies above Ukraine today. Another area where the East and West had a serious martial showdown was in Infantry Fighting Vehicles (IFVs).

The M113 armored personnel carrier was a workhorse throughout the war in Vietnam, but it was basically just a big aluminum box with tracks and an engine. The ACAV kits consisted of armored shields fitting up top to accommodate a Ma Deuce 50-caliber machinegun and a pair of M60s. However, this was a makeshift solution at best.

Meanwhile, the Soviets were churning out BMPs. The BMP was a legit IFV with a turreted 73mm gun, a rail-mounted AT3 Sagger antitank guided missile, and firing ports through which Soviet conscript soldiers could exercise their Kalashnikovs. Aside from the fact the BMP was as cramped as a Ringling Brothers clown car and only slightly more survivable in a proper fight, we felt like we were falling behind. The end result was the M2 Bradley IFV.

The Bradley was and is a simply superb piece of kit. Featuring a wicked 25mm Bushmaster chain gun, an external two-shot TOW missile launcher and room for a crew of three along with half a dozen kitted-out grunts, Brads are kicking Russian butt in Ukraine as I type these words. However, the M16A1 rifles issued to American infantrymen did not well-accommodate a firing port in such cramped quarters, particularly if the interface also needed to help minimize such vile stuff as nerve gas and radioactive fallout. The flower of American engineering prowess set about designing a solution. That solution was the M231 Firing Port Weapon.

The competition came down to the standard WWII-vintage .45-caliber M3A1 Grease Gun, a curious German offering based upon the roller-locked HK33 assault rifle, and a unique M16 variant designed by Colt. The Grease Gun and HK weapons both fell out of the running for various reasons, leaving the Colt gun ultimately to see production. The end result, while not terribly effective, was mechanically fascinating. The development process took five years and the gun was formally adopted as the M231 in 1979.