I picked one up a couple of years ago at the San Diego gun show. There are legal ways to own one in California. The main thing is that it must have a non detachable 10 round magazine. I have an Smith & Wesson M&P 15T. It is made with a detachable magazine, but to make it legal you just need to replace the magazine release button with one that has a locking system that requires a tool to remove the magazine. Here is an example Mag Lock. To keep it legal you CAN NOT remove the magazine, even to load it. You must top load, a real PITA. But when your shooting out in the desert and there is no one around for miles to see you it only takes an allen wrench to back off the screw and the button works like normal:o.