Piston systems do not make gas go away. They merely vent it in different locations. Here, the gas is venting directly behind the front sight, as it is meant to. Photo from Gun Digest Book of the AR-15, Vol. III
Need Gifts? Check Out the New Gun Digest Easy Gift Guide
Here are 20 photos of HOT AR-15s from Patrick Sweeney's Gun Digest Book of the AR-15, Vol. III. Who says ARs are ugly?