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How Does it Work: Long Stroke Gas Piston

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The long stroke gas piston system was in its heyday about 50 years ago, and was popular in both rifles and machine guns. The principle is that the gas piston is fixed to the bolt carrier, and both cycle rearward for the full length of the cartridge upon firing. The system was used in such distinguished designs as the M1 Garand, Kalashnikov, Browning Automatic Rifle, and ZB/Bren light machine guns among others. By including the mass of the gas piston in the reciprocating parts, the long stroke system potentially carries more momentum when cycling, this improving extraction and feeding. This generally comes at the cost of increased perceived recoil, as the extra mass impacting the rear of the receiver at the end of travel is felt by the firer.

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