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John R. Haynes 20mm Gun Kit
Alex Johnson


In my twenty years of modeling, I have shared the frustration of others who seek well-detailed armament for PT Boats in 1/72nd scale. The gun kits I grew up using tended to share a lack of detail and poor casting. From the moment I saw this new gun kit, I knew it was a winner. Clearly John R. Haynes had the modeler of small combatant vessels in mind when this Mark 10 20mm gun kit was designed. PT Boats used the Mark 10 as a lightweight replacement to the early Mark 4 mount. This gun kit will serve the PT Boat modeler in a variety of applications.


The product contains cast parts and a photo-etched brass sheet. The cast gun kit has three pieces: the gun body, the cradle and the tripod mount. The gun body has a great deal of detail including breech, barrel, ammunition drum and sight. The cradle or yoke is accurately shaped and the tripod mount contains perfectly sized legs to simulate the angle irons used on the prototype. The detail on all three parts is impeccable. I marvel at the quality of the casting and the absence of "flash." Quite simply, the gun is ready for assembly right out of the package. The photo-etched brass sheet includes shoulder rests, two sight rings and an armored shield. Again, there is no detail omitted and these parts need almost nothing except removal from the sheet.

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The cast gun parts required minimal preparation and took just a few minutes to be readied for assembly. I gave them a token going-over with a file and sandpaper. There were just a few minor blemishes around the edges. Since my model was a PT Boat with a field-installed 20mm gun, I removed the sight with a knife and file. Also, I did not need the shoulder rests for my application. The photo-etched parts are great and I wish they had been utilized. Rest assured, they are in my box of scrap parts and will be used in the future. The last step was attaching the cradle to the tripod which I did in short order with CA glue.

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After the easy preparation of the gun parts, I sprayed the components with gray Krylon primer and allowed them to dry. The stand and cradle subassembly were painted Deck Green to match the rest of the boat and the gun itself was painted with Gunmetal. Once the gun dried I applied sealer. I was amazed how well the airbrush brought out the excellent detail of the cast parts. By spraying on several light coats, nothing was lost.

Final Assembly

With the paint dry, final assembly simply involved using a small amount of CA glue to hold the gun at the desired angle on the yoke. In this case I chose to have the gun pointing straight up. This was often the position 20mm guns on PT Boats were locked when not manned. It sure looked sharp and I couldn't wait to get it mounted on the deck of the boat.


My review of the John R. Haynes 20mm gun kit is excellent. The detail is amazing, preparation is minimal and the gun will serve the small combatant modeler well in a variety of functions. In future applications I plan to also use the gun for the shorter Mark 14 mount. By simply shortening the legs and mounting the tripod on a round base, it would be ideal. Also, the tripod could be used to mount 37mm guns. While the automatic M4 37mm gun was sometimes set on locally fabricated pipe mounts, PT Boats often used the Mark 10 or Mark 14 stands. This 20mm gun is well-made and will be welcomed into the modeling fraternity for its quality and versatility.