As far as I know there isn't one.
Also, it'd be impossible to properly replicate the firing modes, on full auto the cyclic rate is only around 600rpm, whereas on 2 shot burst it is 1800. Without a very fancy mosfet set up, anything like that, that involves having two different rates of fire, would be impossible to pull off.
Gas gun maybe, but then I'd want to see the barrel assembly moving to reduce recoil and speed up the cycling process, as per the real one, which I highly doubt is possible with such a small gas supply in the magazine.