It seems like a very undersized cannon wall with a huge heat sync. I know cannon can get hot from repeated firing, especially if out in the sun, but heat is not as big a safety issue as the strength of the chamber. It also looks like the trunnions are secured to a couple of fins, rather than the body of the tube. Neat looking design, but I wouldn't want to be anywhere around it when fired. I'd consider it a "fantasy" cannon.