“That’s the first thought that occurred to me, using fusion for railguns on naval ships. As for me, I’d like to have a fusion-powered railgun on my pickup truck. Just to plink bottles or something.”
I’d rather have an infrared semiconductor laser in the low megawatt range. That would be a very quick end to the Drone Era :).
That, you can make right now. Plenty of YouTube how-to-do-it videos on how to modify low-powered lasers and boost the output, enough to burn holes in stuff. Portable power is a problem, so megawatt lasers would be a tough project. Your utility bill will be a shocker.