It is still a gas system just that it vents in the forearm instead of in the receiver like a standard AR. You can do the same thing by purchasing an Adams gas piston conversion kit for your Ar15.

http://www.adamsarms.net/

If it's like the rest of the new Ruger guns that they introduce they will advertise the heck out of it and then drastically under produce it and you will have to wait months upon months to get one.