It seems that not only the US Navy is experimenting with electromagentic guns. Personal inventors are doing said same. I present you with the CG-33 Portable Coil Gun, the best EM gun to be presented to the world as of yet. And the funny thing is, it was made by an independent inventor named Jason using simple OTS (off-the-shelf) electronic components. These include a 12V Nickel-metal battery, a series of capacitors and a bolt action loading system.
You might want to study up on mechanical and electrical engineering before attempting to build one of these, but the results are impressive. I wouldn’t be surprised if Jason got a call from Heckler and Koch or some other gun manufacturer in the near future!