| 摘要 |
<p>A valve body 122 is in a cylindrical shape and communicates with the rear-side end of a barrel 113 on the front side. The valve body 122 forms an air chamber 126 therein. A discharge valve 123 is positioned in the valve body 122. The discharge valve 123 is hit by a bolt 121 from behind and thereby opens or shuts the communication between the barrel 113 and the air chamber 126. When the bolt 121 makes forward or backward slide movement, the valve body 122 is fit into a first opening 121g at the front part of the bolt 121. The cylindrical portion 121h or the closed end 121d of the bolt 121 is provided with a second opening through which the air in the bolt 121 flows in or out.</p> |
