The full auto board will have a switch under the left grip. It will give you semi,burst,full auto. Unless you can get a Gale Force board you are S.O.L.
You might be able to buy a board from Damian at Scenario Dreams. It's a multi use board. If I'm correct and it's been a few yrs, you are at the BPS you want with a stock Rainmaker board.
Hope this helps.