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An explanation I posted on PBN......
The bolt is pumped back by the pump arm, pushing the ummm, lets call it the powertube, back, allowing the dump chamber to fill, and pressurizing the lpr, which in turn, pressurizes the 3-way.
Opening the 3-way allows the Low Pressure air into the can, pushing forward on the sail, overcoming the balanced pressure in the dump chamber (I made sure to make the surface areas in the dump chamber even, to have balanced pressure). When the powertube moves forward, air is released around the stem, flowing through the tip and pushing the ball.
Yes, you could pull the trigger before you get the bolt all the way forward, but you can do that on a sniper as well. Although.... in the more advance drawing of my idea, the pump rod rubs along the top of the trigger. Not until the pump arm gets all the way forward does it allow the trigger to be pulled... thus stopping you from firing until the bolt is set, and creating an autotrigger!
This pump spool is similar to a pump mag, because mags are also spools, just with an inverted tail. This idea of mine differs in that it has a pneumatic trigger which is inactivated until the dump chamber fills. Cool huh?
It's also different than a pump mag in that the bolt would be fully connected to the pump arm. In a pump mag, the pump arm just pushes the bolt back and it resets against the sear (my design has no sear!)... meaning the pump mag is an open bolt pump. You cannot have the mag be a closed bolt pump without serious mods, as the bolt being forward means the valve is open. My two part system allows for a closed bolt spool valve.
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