AR-15 Gas System

Transcript

AR-15 Gas System As the expanding gases propel the  bullet down the barrel, a portion escapes through the gas port. This high pressure gas quickly  travels through the gas tube, leading to a chamber between the bolt and the carrier. The dwell time is the time the bullet spends

between the gas port and the muzzle. The pressure from the gas trapped behind the bullet is necessary to cycle the rifle. The chamber between the bolt and carrier  acts as a pneumatic cylinder.

Since the bolt cannot move forward, the pressure forces the carrier to the rear. As the bullet clears the muzzle, the pressure drops and at this point the carrier has  picked up enough inertia to retract the bolt. The two vents on the carrier

pass over the gas rings on the bolt releasing the gases from the chamber. The bolt carrier continues to the rear  as it extracts the empty shell case.