A method and apparatus providing an action system for a firearm. The action system includes a primary roller-lock mechanism located rearward of an ejection port. The primary roller-lock mechanism includes a bolt and a first primary roller caged within the bolt. A bolt carrier ramp is attached to a bolt carrier. A barrel extension ramp is attached to a barrel extension. The first primary roller, bolt carrier ramp, and barrel extension ramp cooperate to effectively delay movement of the bolt and bolt carrier in response to firing of the firearm.