Newby AR15 owner question. Which way does the air travel in the gas tube and where does it go? I'm assuming it passes thru the bolt carrier key and into the tube, along the length of the barrel, thru the front sight post, then where? Right back into the receiver??? Is that why this rifle gets so damn dirty? Does the gas exit the rifle somewhere and if so, why not thru a hole in the front sight post since this is where the tube runs to.
Also, I see that Fulton Armory sells adjustable gas tubes. Any benefit to these for anything other than DCM?