Coaxil Piston Gun Questions/Suggestions

[LCTChamp]

Gun completely built but piston wont seal

I have checked for particles and cleaned it which didn't fix the issue.

Ideas?

[Gun Freak]

Pictures...

[jackssmirkingrevenge]

Breech end not cut at 90 degrees?

Not filling fast enough for pressure to build up?

[LCTChamp]

Pictures will come but I cant seem to find my camera.

Breech end was cut in a mitre box and then sanded. Im filling with a large air compressor, so I don't think that is the issue. Im dumbfounded

[jackssmirkingrevenge]

Is the barrel properly centred and supported? Could the washer keeping the sealing face rubber be making contact with the breech edge?

[Technician1002]

You may need to lap the valve to remove any surface imperfections from the valve seat or valve face.

I lap all my non QDV valves.
http://www.youtube.com/watch?v=fhXsH12R ... r_embedded

You can see the ring on the face of my piston where it was lapped on the valve seat seal.

[LCTChamp]

Is the barrel properly centred and supported? Could the washer keeping the sealing face rubber be making contact with the breech edge?

Ahh What should I use as a barrel support?

[jackssmirkingrevenge]

Ahh What should I use as a barrel support?

It could be as simple as three screws at 120º in the breech end, adjusted so they protrude enough to keep the barrel centred, and epoxied to prevent air from the chamber leaking into the barrel. They also provide a convenient "projectile stop" keeping whatever you muzzle load from going into the chamber.