M55 Cal. 50 Machine Gun Trailer
Modeling the U.S. Army in WWII

Hobby Fan

This is, for the most part, a well executed styrene and resin model of the rarely seen towed version of the quad .50 Maxon mount that armed the M16 halftrack. The gun assembly in this kit, molded in styrene, had its origins in AFV Club's Vietnam era M35A1 Guntruck.

At the end of this construction article, I've listed some web references. Roy Chow also provided me with images from the technical manual. There are some differences between all these references—and the kit as well—that I didn't take additional time to track down and reconcile. This is a kit that improves with a little bit of TLC, particularly with regard to the power plant in the rear end.


After Army experiments with aircraft mounts for a twin .50 machine gun antiaircraft weapon proved successful, the W.L. Maxon Company was contracted to develop and produce a vehicle-mounted version. This resulted in the Twin .cal .50 Machine Gun Mount M33, also known as the "Maxon mount." It was installed in the GMC M13 White halftrack, and the M14 International Harvester halftrack (the old Monogram kit was based on one of these vehicles). Konrad Schreier, Jr., states the M13 saw limited use in North Africa, while Steven Zaloga says they didn't see combat until the Italian campaign. In any event, it didn't take long for the Army to figure that adding two more guns might make the Maxon mount even more deadly.

Adding a protective armor shield for the gunner, the new quad .50 was formally known as the Multiple Machine Gun Mount M45 when it went into production in 1943. It armed the M16 halftrack as we know it in the Tamiya kit.

The Maxon mount next found a home on the large two-axle M17 trailer, which was designated the .50 Multiple Machine Gun Carriage M51.

The U.S. airborne asked for a smaller version that could be transported by glider or cargo aircraft. Situated on the Trailer M20 and minus the armored shield, this version was the .50 Multiple Machine Gun Carriage M55. At a little more than 3,000 pounds loaded for combat, it could be pulled by jeep. Firing at a rate of 450 to 575 rounds per minute per gun, this weapon was particularly lethal when applied to ground targets in the field.

Construction of the Maxon Mount

As mentioned, the kit's Maxon mount and guns are molded in styrene. The trailer and ammo cans are resin, and a thin black plastic tube is provided for the tail light's electrical connection. The resin pieces were cast reasonably well: there were sizeable air bubbles on the hub caps of each wheel which needed some repair, but other details were good. There was also a small piece resembling a retaining lock that was missing from one of the cylindrical sleeves on the trailer body. Some putty had to be applied to some slight sink marks on the corner bracing of the side trunnion assemblies.

Assembly begins with gluing a very small butterfly thumb trigger to the rears of each machine gun. DON'T DO THIS! In all of the photos I found at the aforementioned sites and others, as well as those in books from Zaloga, Berndt, Schreier, and The American Arsenal, there was only one contemporary photo of a restored quad .50 that showed the thumb trigger on the set of MGs. The tech manual and a few period and contemporary photos of restored quads show a solenoid where the thumb trigger was found on non-quad .50s. However, guns in many other images, both period and contemporary, are without solenoids. So, I did not use the butterfly triggers. Nor did I install solenoids, because I could not get a complete visual understanding as to how they were wired into the apparatus, but I can add them later. The guns also lack the barrel changing handles, but those don't appear consistently in period photos. Be sure to use the tip of a new hobby blade to hollow out the business ends of the gun barrels. The kit includes flash suppressers, and shows them on a finished model in the instructions, but I believe this is a post-WWII feature.

Steps two and three adds the gun mounts to the trunnions. There are a number of small parts that have to be properly aligned in order for the guns to rest correctly. I dry fitted the MGs in place while the glue on the mounts was curing to try to keep everything positioned. It's a bit of a challenge since the pieces are in close proximity and the guns, which have locating holes that mate with small nubs in the front mounts, tend to swivel up and down and are easily nudged out of alignment. The other option is to permanently glue the guns in place but that would make them difficult to paint.


Setting the trunnion assemblies aside to dry, I moved on to the next step, which adds the foot rest, control post, and bolt strips to the base. The two strips have to be bent around the circular base, which is a bit of a trick as they are fairly thick styrene pieces that could snap without care. I shaved down the backsides slightly and tried to give some curl to the strips, but the ends still wanted to lift up after being glued in place. I had to use a couple self-closing tweezers to held the ends down. This detail might be better served by strips of photoetch, but the end result was quite acceptable. (The kit includes a couple additional bases that were used to elevate the vehicle-mounted quad.)

Step five brings the base, trunnion sides, supports, seat, and front shield together. Again, once this built, it could be challenging to paint, so I added one trunnion and the supports, and then painted this subassembly and the other pieces separately. Photos show the seat is canvas (I recall seeing some models that assumed it was sheet metal, but I haven't seen any photos that support that). I added some thin black wires to power the trunnions (tucking the loose ends under the seat. The control handles were painted black, as were two buttons on the switchbox, and the center switch was painted red. The canvas seat was painted a greenish khaki color. If you want to build the M45C airborne version, you'll want to leave off the gun shield; I used a dab of super glue to hold it in place for this construction.

There are 20 small bolts molded onto one of the styrene sprues, but no indication in the instructions as to what they are for. I did notice in the website photos that there are four bolts on each of the four horizontal corners of the Maxon mount, which are missing on the kit parts. Are the bolts for this use? Nothing else was apparent in the instructions, so I carefully sliced them off and set them in place with some super glue. It's a good thing there were extra bolts, as four of them decided to venture into other realms of my work space. Down to no spares, that last little bolt had a lot riding on him!

You get to add a little more color to the parts that make up the power plant in step six. The battery is black, but make sure to paint the retainer that runs around the top of the battery olive drab. The power charger is a gas-fed generator whose features differ between the tech manual images and contemporary refurbished vehicles, which the model more closely represents. The main differences are the muffler positioned on the left side in the TM, and on the right side in recent photos; and the gas cap is on the right side in the TM, but centered in contemporary references. Another item missing from the TM is a foot step extended off the base by the battery and generator. Again, these may be due to Hobby Fan relying on a Vietnam War vintage quad as a reference; online images that suggest WWII vintage vehicles are actually post WWII; or specification changes and upgrades or changes between manufacturers during WWII are not reflected in the tech manuals (i.e, The American Arsenal shows a trapezoidal shaped trailer body, but does that reflect an initial demonstration version or the definitive production version?).

Another notable difference is that the junction box, which is on the bracket of piece V2, had a voltmeter display, which is not featured on the kit part nor in refurbished quads (some have a circular plate over the opening, others have a blank side with no evidence of the voltmeter). I opted to include a small gauge from the nice U.S. Internal Stencilling set from Fingerprint Designs. I also added wiring for the battery and power supply.

In step seven, the gun mounts are joined with the trunnion via the sight brace; the kit suggests not gluing the trunnion mounts in place so the guns can swivel up and down, but I glued them down since I was building the kit for travel mode rather than emplaced. The sight, part V9, in reality had a clear, angled disc at the bottom, which reflected the target image for the gunner to see. This is all green styrene, of course, but I bought a little more realism by carefully drilling out the center of this disk with a pin vise. I painted the disc silver, and when that was dry, I placed a small drop of Testors clear glue in the center hole, which was small enough for the drop of glue to adhere to. After that dried, I gave it a dab of gloss lacquer, and I'm very pleased with the final result. It's certainly much better than painting the flat disc silver or trying to cut out a small piece of clear styrene and inserting it.

Note that the instructions in step seven show the two additional bases in place; I think this was just cribbed from the previous guntruck kit's instructions. A little Photoshop work could have cleaned this up.

Construction of the Trailer

The trailer finally comes into the picture in step eight. While it looks trapezoidal in the M55 image near the top of the page, Hobby Fan's kit portrays the trailer as it was in the WWII era TM 9-233. Construction here is pretty straightforward once you decide if you want to have your quad on the road or deployed for action. In the latter instance, three jackstands attached to the trailer were used to stabilize the gun. Hobby Fan provides two sets of jackstands, retracted and stored for travel, and extended for action. The box photo shows the wheels removed altogether in the deployed mode, which was the common practice described in The American Arsenal.

In the final two steps, a resin base plate is fixed to the trailer, the electrical cable is added (you may want to wait with this until after the trailer is painted; I forgot to add it before I shot these photos), and the four M2 ammo chests are placed. In my construction, all the painting and much of the weathering was completed before I glued the painted and weathered MGs to the mounts. I carved off a small rectangular feature on the sides of the ammo chests where they are glued to the trunnion brackets, since this feature impeded proper alignment and broader gluing surface, and could not be seen.

There are no decals with this kit so you'll need to scrounge up some serial and unit markings from other sources if you desire.

Overall I enjoyed building this kit, and it's a good rainy weekend out-of-the-box project. I'm planning on using mine in a towed situation, and Tank WorkShop's .50 Cal Ammo Containers will probably be loaded in the towing vehicle.


The American Arsenal: The World War II Official Standard Ordnance Catalog of Small Arms, Tanks, Armored Cars, Artillery, Antiaircraft Guns, Ammunition, Grenades, Mines, etcetera, introduction by Ian V. Hogg, Greenhill Books, 2001, ISBN 1-85367-470-2.

American Tanks of WWII, by Thomas Berndt, Motorbooks International, 1994, ISBN 0-87938-930-3.

Maquette Garden, maquettegarden.free.fr/Vehicules/Half-track%20M16/index.xml.

Standard Guide to U.S. World War II Tanks & Artillery, by Konrad F. Schreier, Jr., Krause Publications, 1994, ISBN 0-87341-297-4.

SVSM Model Club Photo Gallery, svsm.org/gallery/m16.

Tanxheaven, www.tanxheaven.com/ljs/halftrackus/halftracksusaljs.htm.

U.S. Half-tracks in Combat 1941-1945, by Steven J. Zaloga, Concord Publications, 1999, ISBN 962-361-654-6.

Sample kit provided by Hobby Fan.



Modeling the U.S. Army in WWII © 2002—2007 Timothy S. Streeter