3D Animation Shows How an AR-15 Semi-Automatic Rifle Works
A simple shot of a round from an AR-15 rifle requires a series of perfectly timed events that take place within a fraction of a second.
In order to ensure that the gun fires smoothly, a small portion of the hot gasses which propel the round are diverted from the barrel and brought directly to the Bolt Carrier Group (BCG). This automatically chambers a new round.
Watch this 3d animation of how the basic AR-15 semi-automatic rifle operates as it fires.