Small coaxial

[rixth]

Negative
(msg to short)

[jackssmirkingrevenge]

that might be your problem then. Find a washer that is slightly smaller than the inner diameter of your barrel and fit in place, see if that helps.

[rixth]

I'll see what I can do tomorrw (it's dark now).

What function does the washer hold?

[jackssmirkingrevenge]

Without the washer, air can get between the sealing face and the piston body, with the result that the face is "sucked in" to the barrel and starts to leak above a certain pressure.

[MrCrowley]

If it still leaks after that, air could be leaking through the piston and out where the bolt head holds the washer in place, epoxy that up if necassary.

[rixth]

I tried filing the piston to make it fit in the pipe, it does but the seal still ain't flash, plus I have to manually press the piston up against the barrel every time. I think I might sleeve a bit of PVC in there, just so I can get smooth sides then make the piston in that...