SpudFiles

What gun have you used at high pressure?

Where did you buy it?

BoyntonStu

Well, I've used a husky air compressor blowgun:

to 400 psi just fine, even though it says 90 psi max It is easily modifyable and when I use it for piloting piston valves I just cut off the bottom half. I buy mine at home depot in the U.S.A. Baby!!!!!!!!!!!!!!!!!!!!!!!! Sorry, I'm gettin excited lol.

same used to 550psi

For pressures like that its probably more economical to either build a push button valve with a lever, or build something like the valve BTB built that balances out forces so that you only need to overcome the force of the spring used to keep the valve closed.

The valve maverik suggested will sometimes work to pressures that high but its also quite possible that it will leak at around 200 psi.

Yeah, I had a bit of trouble with one of mine, but I think that was because I screwed the hammer assembly down to hard after modification, and It leaks pretty bad now.....damn.....6 hard earned bucks down the tube, but anyway, other than that, I've never had any problem taking them regularly to 300 psi (and I've taken them to 400 psi on a few occasions, again with no leakage). That's not to say It is gonna work every time, but I think it's a pretty good quality blowgun, and it's only about 6 U.S.D.(with tax)

But the title says 500-600!

It would be simplest to use a ballvalve.
A pushbutton valve would work as well...the one I made at least..