SpudFiles

Have you correctly sunk it into you pvc (if you are using pvc)?
Have you just ripped the valve of the closest bike tyre?
What pressures are you operating it under?
if you can post your gun so i can have a look at it just to see.(if you have, post a link)

How i did it was to go to the nearest bike shop and ask for the most shiny one. then i drilled a hole in my end cap that was slightly smaller than the bike valve and pushed it in. Then i used leftover epoxy resin from my surfboard repair kit to seal the deal. If you want you can rip it of the closest bike, that also has worked for me well. the trick is to leave a circle of rubber as large as the end cap so that when the pressure builds the rubber acts as a kind of seal against the end cap. In that case also use a glue to finish it of just in case.

I'ts a schrader valve, not a shnader valve.

yer i got a bike valve (from the nearest sisters bike hehe), putting it into pvc, like 100-150 psi of pressure.

if ur gonn use a pop valve, u better use some eproxy to make sure its gonna stay airtight. the valve ima using atm is a chrome tire valve that just screws in with thick rubber seals, the kind u get in big truck tires. picked one up from the local tire shop for 4.50AUD, so not that expensive.