My Dad much admired the “quad fifty” from his time in Vietnam seeing it in action. Once telling me about watching one fire at a distant jungle hillside and how large trees would be cut down and everything around chewed up. Below is a good article about the M55 from the Rock Island Museum blog.
By G. Neuhaus
How do you increase the firepower of your magnificent .50 cal. M2 Browning Machine Gun when there’s only room for one finger on the trigger and someone else has to feed you the belt so it doesn’t get kinked up? You climb out of your foxhole, take it off the tripod, mount it on a carriage, and stack up four of them, ready to go. Thus you have the M55 Quadmount.
In WWII, one M2 did not have the rate of fire, at 450-600 rounds per minute, to take out a plane, but four of them concentrated on one aircraft could bring it down. And there was a lot of room on that mount for large cases of ammunition. Each gun had its own box right next to it that could hold 200 rounds. The system had two pairs of machine guns separated by an armored plate to protect the operator sitting in the middle. He could swivel the mount all the way around, 360 degrees, and elevate the guns anywhere from -10 to 90 degrees. Most operators fired the guns in pairs, either the uppers or the lowers, to prevent all four from overheating at once. The system was designated the M45, and it was used to great effect in WWII.
In the Korean War the mount was changed to a round trailer design and called it the M55. During the Korean War, one of the Rock Island Arsenal’s many projects was working on these .50 cal. multiple machine gun mounts.
Then in Vietnam we loaded it in the back of a deuce to cart it around. Once again, jet technology was flying faster than our old anti-aircraft artillery could shoot it down, and the M55 was then used for ground combat and escort duty against enemy troops.
GI’s called these gun systems and their mounts “Meat Choppers”, and a trip to the Rock Island Arsenal Museum will show you why they were so effective in their time.