A gas piston setup would eliminate the gas in the face, but would cause new problems of its own. Most notably, the infamous "carrier tilt" prematurely wears out the receiver and bolt carrier. The mass of the gas piston will also increase felt recoil and muzzle climb a bit. But that can be corrected with a muzzle brake.
That said, a few companies sell charging handles specifically designed to prevent the gas-in-the-face problem. Do a Google search for "gas buster charging handle". You can even DIY one, if you're so inclined.
[This message has been edited by Blacktree (edited 06-26-2012).]