I worked for Spence Rees that made all the awesome fake guns for Barbie III including the 75mm cannon. On another project, he made a fake gun with an internal piston that would cycle using compressed air from a scuba tank. He said it sure made the kids scatter! Another story was when Spence got pulled over in Sugar Grove and had to show that the .50 cal on the back of his Willys indeed had a PVC barrel inside the cooling jacket. Last time I saw Spence he was working on his Beech Model 18, a 1/5 scale Bearcat model, and his M3 halftrack. Will look for pics.