direct impingement or gas piston for .308?
For an AR type semi-auto in .308, what are the advantages of a gas piston with action rod as opposed to a gas block and a tube to carry the gas back to the bolt? Wouldn't a piston set-up keep the action cleaner?
And for the AR platform, why isn't the gas block closer to the muzzle? I remember the M1 had the gas piston almost at the end of the barrel. The M1A (or M14) has the piston farther in, towards the receiver, but not nearly as close to the receiver as the AR platform, where it seems to be about halfway between receiver and muzzle. It seems like putting the gas block (or piston) so close to the receiver robs the bullet of much needed pressure.