M-55 Quad Fifty


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.



    • No. The crew was pretty exposed. But once firing was able to regain fire supremacy in short order. When used in ground deployment against surface targets they were best used as part of a system. Oh they looked and sounded ferocious and were lethal but without an infantry screen and Artillery support, ideally from a Duster, they were vulnerable. However, going against a loaded Quad Fifty, all guns charged and with an initial load of four hundred rounds, not something conducive to living a long life.
      Many an outpost and fire base was saved by crew members getting back to the Quad after being blown off, and many a convoy saved by the crew members’ actions to keep those weapons firing.

      The guns had to be kept loaded, retrieve the ammo can, undo the lid latch, pop the top off by knocking the to the side so that it disengaged from the half pin hinge, pull the old can out of the gun’s ammo tray, place the new ammo can, link the belt or open the cover and place belt, close cover and charge gun with the charging handle. Repeat. Hot shell casings ejecting and collecting under foot, empty ammo cans and lids being thrown off out of the way. Deafening noise. If the loader was lucky other GI’s would be popping off the lids to the Ammo cans and lifting up to the firing platform whether it be the truck or the Quad mount on the ground. And hopefully the mount had all new barrels, which occasionally happened and all the electric firing solenoids worked. And someone was providing you with protective fire to keep people from sneaking up on you.

      The fifty caliber 100 round ammo cans weighed somewhere around 25 to 30 pounds.

      And then afterwards, you got to clean everything, dis assemble and clean, re assemble and check for correct tolerance and performance, fill out action reports, rounds expended, maintenance logs, account for anything missing.

      E/41st Quads (motor pool)

      Go to the NDQSA (National Dusters Quads Searchlights Association) website for more information.

  1. Guess I’m just not american enough, but I never saw the point of one of these compared to autocannons. With no explosive charge the ‘fiddy’s only advantage over .30 cal guns seems to be range and armor penetration.

  2. When I was a kid, I knew Vietnam vets who had used Quad-50’s in trucks for convoy security. Apparently, the miniguns were the psychological weapon at night, but when it came to “destroying stuff,” the Q-50 was the bee’s knees.

  3. My all-time favorite with this is Dennis Hopper in “Waterworld” watching one of these things at work on a barge when Kevin Costner distracts or fools the operator into shredding Dennis Hopper’s command boat. Best line from Dennis Hopper “somebody STOP him!”… nope, too late 🙂
    Good times though in a crappy movie.

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