| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly safety and reliable maintenance-free gas flow unit for a shot gun having a self correcting function optimal for prolonging the lifetime of components, a self-cleaning function of enclosed components, and a simple, lightweight and economical structure having no effect on the limit of ammunition capacity. SOLUTION: The gas flow unit for a semiautomatic or automatic shot gun comprises a gas flow cylinder closed by a flange having a gas exhaust port 17 around a magazine at a forward part, and an annular valve 18 facing the cylinder and moving in the axial direction to control opening/closing of the exhaust port. The valve 18 is sustained at the close position by a compressed spring (19) and moved to the open position when the gas pressure in an expansion chamber 14 increases over a specified level.
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