SpudFiles

judgment_arms wrote:LGM, unless you can work with 1000psi I think, for simplicity and safety’s sake, keep it in line. And if your gun was not designed to use Co2 do not use Co2, Co2 guns and pumpers use different valves, a Co2 valve MAY work in a pump pneumatic, but a pump pneumatics’ vale is not designed to take the cold generated be Co2.

Jrrdw, although this page is an explanation as to why this type of valve “squanders air”, it should answer you questions as to how this type of hammer valve works.
Crosman airgun forum

No, that page was more about the travel of the projectile as opposed to the amount of pumps, and about hop ups. But thanks for the link.

Jrrdw, near the top of the page is a diagram on “why dump valves squander air” and although it’s about a modified dump/hammer valve, it shows how they work. But I’ll sum it up anyway:
One, the hammer is cocked, and the gun pumped up to the desired pressure.
Two, the hammer is released and slams into the “firing pin” pushing it forward along with the valve face, the part that sealed the air in, opining the valve.
Understand?

Yea, i get the basic idea of how it works. Thanks, it's a small chamber on a air rifle. With a pump that size, it world take for ever to pump up a big chambered cannon, but i now see where this set up would work very well with a good built mini.

What is a Hammer valve? Sorry if its obvious, but it sounds to me like it is actuated by something hitting it (Duh). Does it work well?

Hammer valves are sometimes called “dump valves” but no matter what you call them there usually the kind of valve that is found in airguns. I’ve both posted a link and given a brief explanation on how they work.

If I were to bring a small metal chamber to 500-700 psi using dry ice and allow the valve enough time between shots to warm up, could this be safely fired? I will not be using the original chamber.

Wow, thanks guys.... Thats WICKED simple...... ill work on a semi-auto concept witht that it looks easy as pie.

Yeah sorry it took so long, been busy.
LGM, for the last time, the valve is the chamber! If you remove the chamber you’ll ruin the valve. I believe you have the chamber confused with the pump tube.

VH_man, semi-auto, how do you plan on accomplishing that?

Its simple. the pressure released by the hammer hitting the valve should be enough to drive the hammer back to its sear... i think. correct me if im wrong.

The hammer is spring powered, and hand cocked when ready to fire.

Yeah, but is the air released by the hammer hitting the valve enough to make the hammer get coked again?

hmm
an interesting problem
it does depend on the caliber
if i were in your condition, i would custom machine a nice new receiver out of solid aluminum billet
but, most people do not have a nice metal machine shop......

depending on the ideal operating pressure, you may consider using a paintball regulator in conjunction with an HPA tank
ill think about possible solutions
just, try not to use 1k PSI air unless you built everything VERY nicely
it is doable, but if it messes up it may shoot fragments everywhere at speeds nearing Mach 1. (not fun)

good luck!!