Slick! You just need to find some really big-&$$ springs to make that work @ high pressure. That is pretty simple, should have constant shot power, and it has the advantage over jack's rattlesnake in that the porting to the barrel is straight with no dead space. (That's the valve from that huge nerf...

Well gents, I've just enrolled in a machine tool class, so there's a chance I might be building something soon. I need to come up with a project. I'm thinking semi or auto. I've got three ideas: 1) Jack's rattlesnake 2) a pump-action or self-cocking hammer-valve gun 3) maybe a hammer-triggered pisto...

peizo is by far the most effective way of converting mechanical work into high-voltage electricity. Probably more efficient is frictional generation of static electricity, but that's cumbersome and unreliable. The hand-crank flashlights all use a small, low-voltage (3-5V?) dynamo to charge a battery...

Ok, I got this idea from the assisted blowback that al-xg came up with here http://www.spudfiles.com/forums/14mm-automatic-air-rifle-t19321.html here's my modification of it: use a slide valve to control the airflow, and incorporate that into the bolt. http://xa4.xanga.com/eb1f747406432261990228/m20...

Dang that is freaking amazing! Loving the max ROF test there! 8)

Flipping awersome! Very good work man! It's neet that you can see the ammo loading, that's a nice touch.

That looks really dang cool! 8) I contemplated building a hammer-triggered multi-shot piston gun, but I never could get reliable re-seating from a piston. That's going to be one heck of a gun when you get it working; and it already looks the part!

Jack! Woohoo! You finally made the stinking pop-off gun work! Way to go! :D And it turns out the extra complication of the linkage from the piston to a valve at the inlet to the firing chamber was unnecessary, huh? (That is, the blowgun doesn't overwhelm the valve and make it fart/stick open.) That'...

That's very nice! I really like how you got the chamber right up under the barrel by turning the valve sideways. That's pretty slick, especially in copper.

Oi, so it's a blowback hammer valve! Nice work! Do you regulate the CO2, if so, what psi?

Good work! So, IIRC the last time a design like this came up, people decided that it wouldn't work unless there were some sort of valve coupled to the piston to shut off the air flow from the compressor/reservior to the firing chamber. Looks like we were wrong!

Nice work! I like the judicious use of pre-existing components (ie, modding the nerf gun)! It makes me want to try my hand at a hammer valve gun.

Yeah, it would work, but I doubt you'd get the same power equivalent out as you would if you shot a single large projectile. I haven't done the math, but you do loose heat energy from the combustion gasses the longer they stay in the chamber. I think it's "worth a shot" though, not very complicated!

Reminds me of this 10yr old friend of my brother, we did a little chemistry demo w/ baking soda and vinegar. Then when he found out we had some gunpowder too, he wanted us to mix them together b/c ,of course, it would be more impressive than either gunpowder or soda/vinegar seperately

Al-right!!! that looks awesome. So, how many bbs per air burst from the QEV?