Tuesday, October 20, 2009

Operating mechanism

The Galil series of rifles are selective fire weapons operated by a Kalashnikov-pattern gas-driven piston system with no regulator. The weapon is locked with a rotary bolt with two locking lugs that lock into recesses milled into the receiver.

When fired, a portion of the propellant gases are evacuated into the gas cylinder through a 1.8 mm (0.07 in) port, drilled at a 30° angle in the barrel, and a channel in the gas block. The high-pressure gases drive the piston rod (which is attached to the bolt carrier) rearward. During this rearward movement, a cam slot machined into the bolt carrier engages a cam pin on the bolt and rotates the bolt, unlocking the action. The arrangement of parts on the bolt carrier assembly provides for a degree of free travel, allowing gas pressure in the barrel to drop to a safe level before unlocking. To the immediate rear of the chrome-plated piston head is a notched ring which provides a reduced bearing surface and alleviates excess gas build-up. As the bolt carrier travels back, it compresses the return spring guided in a hollowed section of the bolt carrier and the return energy contained in the spring drives the moving assembly back forward, stripping a new round from the magazine and locking the action. The cocking handle is attached to the bolt carrier on the right side of the receiver and reciprocates with each shot; the handle is bent upwards allowing for operation with the left hand while the shooting hand remains on the pistol grip.

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