SpudFiles

yeah, i think the only thing i can think of to better that would be a burst disk....or a mega light piston.....or just make it bigger...

A mega light piston would help, but not by a lot. I know that HEAL's piston is fairly heavy, but the high pressures and opening forces, along with the piloting valve help negate that nicely.

Bigger is one way of going about it though.

yes, but not practical in the uk unless your made of money.....well in copper anyway

Sweet gun, since you have a slide valve does that mean you could get moe then one shot from the chamber?

i'm gussing no as the slide valve is the pilot

no, it means he can have a air source hooked up and have cosecative shots....just open valve to shoot, close valve to fill

Rag I know that beating a home-made 22mm piston won't be easy, but where I might lack in making a piston (I can, but choose not to) I will make up with the opening times. I am currently drawing up plans for my new gun that I would like to make. I will be a QEV burst-disk gun. sounds whacky but it's feasable.

Hmn..grease as the sealent..makes scense, but 300+ PSI wooshing through there, I'm sure a tiny bit of air would leak, im sure that an O-ring inserted at the back here the barrel slides into would increase preformance. Not toticable, but still by a bit.

yeah, i had to glu my o-ring in at 300psi air has a tendancy to take loose things with it

Silicon grease is pretty good stuff, it will stay in place quite solidly.
It's not completely leak free at 300 psi, but it still holds damn well - the leaks at the breech are minuscule compared to the blow-by on many of my projectiles.

I wanted a pipe/fitting interface like I have at the moment to support the barrel as firmly as possible to help accuracy. The difficulty that arises is that there is no space for an O-ring in the fitting without constricting flow, negating the valve's high power.
So, I think adding an O-ring would likely reduce power, rather than help it.

Hmm, a QEV burst disc valve combo. That will easily win out on opening time, but I think flow would be lower.

@Wannabie: I could get multiple shots with an external gas source, but you could do that with most valves. Slide valves are better optimised for it though.

The main reason was that a slide valve will vent quicker than a blowgun, opening the pilot valve more cleanly, but the straight pull of the slide valve was tempting too.

Ah ok, I guess its better to have the flow out of the barrel more effienct than having it 100% air-tight around the breech.

I did originally try to find a way of fitting an O-ring into the slot where the solder would normally fit in the solder ring fitting at the breech (It is the only solder ring fitting on the launcher though, used only because of it's neat fit into the 28mm pipe the breech loader's made from.)

Didn't work out though.

It's quite interesting how much interest a topic can get with the words "320psi" and "copper" in the title.

I don't think that it was the title as much as the name of the author of the thread that attracted all the views. Joanna talked quite a bit about you, and most of the senior members knew who you were.

Titles do help though, I posted a handheld gun that ran on 500 psi nitrogen and it only got 8 comments. ( It was a very simple design though).

Hmm, I didn't think of that.

Do you have a link to this cannon of yours?

It was just a random thing that I threw together with some parts I had around while working on my burst disk cannon. Here's a link

please, please get some video footage I really want to see something annihilated at 320psi

This is a sweet piece of work, if you live in England where do you shoot it with it being so loud and the distance of rounds?

If it had a stock and its bipod on and a large scope I bet it would feel like an m107 or similar.
Once again top job