..or would probaly explode into my face:
Anyway its a railgun cut on half. In the middle is a plasma generator that forces atoms going up and down by magnets (very powerfull ones). The right part is pretty much the same as normal guns.
You shut a bullet---bullet hits a hot atoms---instanty gets hot to 2000*C and then it goes out at speed faster than sound. It would probaly look like lazer from star wars