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原帖由 wing383 於 14-2-2014 01:40 發表 
想請教一吓，當個bolt向後行時，個飛機仍然索住喺個hopup座度，然後靠條飛機彈弓拉佢縮番入個bolt度，呢個相信係正常現象，但想知道佢後既原因，以we scar為例，佢隻飛機尾有o ring咁，其實係要黎做咩&# ...
To move the bolt backward, you have to eject something forwards.
In a real gun, gas expands as the propellant in the bullet gets ignited, pushing the bullet forward and bolt carrier backwards. As the shooter, you feel the recoil as the bolt travels backwards. In some cases, part of the gas which traveled forwards gets redirected backwards through the gas tube to assist the cycling of the bolt, and through the compensator to exert forward forces and muzzle drop torques for stability.
In a GBB, gas also expands as the gas magazine is stroke. However, if you use the same amount of gas you use to push the bolt carrier backwards to push the BB fowards, you'll probably kill someone. Hence, a valve is place in the bolt nozzle. The valve closes as some gas travel through it to propel the BB, then the remaining gas from the gas magazine would expand in the chamber between the nozzle and the bolt carrier in a much slower manner to maintain pressure and efficiency. This pushes the nozzle forward, which is stuck to the gun body so it's actually pushing the gun forward, and it also pushes the bolt carrier backward. When the bolt carrier has traveled back to a certain distance, the spring in between itself and the nozzle would pull the nozzle back and the whole unit would cycle. When the bolt travels back, its momentum would more or less be compensated by the forward momentum of the gun body, hence a GBB is a giant gas operated vibrator. You can validate my claim by holding the trigger on full auto without shouldering it, it would just go back and forth in your hand (well there is a little bit of gas exerted forwards to generate actual recoil of the gun, but it doesn't take a lot of gas to propel a BB.
You could try and feel the actual recoil on a real firearm by shooting your GBB whilst having its tip placed against a wall or something.
tl;dr
gas expands in all directions; your GBB is a gas vibrator
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本帖最後由 cccarlos 於 14-2-2014 10:02 編輯 ]
