SpudFiles

It says it all but it is a question has anybody made somthing like this?
wel I know of the qevs with a pop off but what about a co axial with a pop of?

EDIT: This what it would look like with a modified blow forward brech the whole barrel would move adding a cool effect nice!
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Hmm, looks legit, but I'd go with and over under piston in a T so you can actually have more than one shot, eh?

Yes, that design has been beaten to death on here. BTB's Marble Machine gun works on a similar principle with a custom pop-off.

you could get more than 1 shot in this and I just did somthing up on ms paint

That looks exactly like something JSR made/is experimenting with.

Well, it may look simple to build a coacial loading like that but in 2D paint drawing its way easyer than in 3D reality.
Do mind that you will have to get the ammo pipe through the wall of the larger bore chamber pipe. Wich would only be accomplised well with a T on the chamber.

I actually am working on something almost exactly like that.
the only differnc is mine is in a tee valve and not coax. Ive been kinda neglecting it lately but ill try to finish it this weekend as I have always dreamed of semi/full auto.

It would work if you balance your flows, it's exactly the same principle as this one.

Instead of moving the whole barrel, why not incorporate a bolt into the piston, as had been proposed here?

JSR, i beleive someone made a semi-auto marblegun using that method.......... I remember it distinctly becuase the poor kids fittings looked like they survived a 3 alarm fire. it worked great though.........

I believe markfh11q was the one who made a semi auto with a qev and a popoff?

The problem I find is that the air resetting the piston causes just enough blow-by past the piston that enough hisses out the barrel and actually weakly pushes the ammo out.
You see that if you load a piston gun and then try to pump it up. The piston tends to not seal quickly enough.

Not if you have a tight fitting piston

...or a high pressured air source.

If all of that is worked out, then you can end up with something like this.

I made a EDIT. /\

/\I made a updated look up /\ that version would have a sealing face that seals the pop off when the piston is piloted this alows the pop off to close so that the piston can move forward.