Manual

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Figures 13: The trigger mechanism in the rear position
The Linkage will pull the hammer in an upward arc, causing it to strike the firing
pin protruding from the rear of the bolt. The firing pin will travel forward a short distance and
compress the priming compound against the primer’s internal anvil which causes the
compound to ignite. The ignited compound then travels through a small flash hole in the
base of the cartridge to the propellant, which will ignite and begin to burn extremely rapidly.
The pressure of the primer will force the bullet a short distance forward.
Figure 14: The bullet begins its journey down the bore
As the propellant burns, it creates gas and rapidly increases the pressure to
around 50,000 PSI, causing the brass cartridge case to expand and create a seal in the
walls of the chamber. This pressure causes the bullet to travel down the barrel at an ever-
increasing rate of speed. After the bullet has traveled approximately 11 inches (280 MM)
down the barrel, the gas will enter a small orifice on the inside wall of the bore of the barrel,
which leads to the gas system.
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Figure 15: As the bullet passes the gas orifice in the barrel, burning gas enter the gas
system
The pressure will very rapidly increase inside of the gas system even as it begins
to vent out of the front of the gas head. The gas will begin to push the short stroke piston
rearward. By this time, the bullet has long made its exit from the rifle’s muzzle.
Figure 16: By the time the gas has opened the action, the bullet has left the muzzle
The short stroke piston will push back on the bolt carrier with immense force,
which causes the carrier to lift the rear of the bolt out of contact with the receiver’s locking
shoulder that keeps the breech closed during firing.