Airgunner solution to valve volume in a cartridge valved Sheridan
Here are a couple modified Sheridan cartridge valves.
The first would be very simple to achieve with a standard PGP2k valve. Note the front left valve, with slots milled into the sides. The front and rear orings would have to be in good shape to hold air, which isn't really the case on the stock gun.
The payoff is a huge valve volume, which would make getting double barrel guns up to high velocity an easy feat.
The second valve has separated the valve body and check valve into separate components. In a PGP2k, the check valve would be replaced by the chamber plug and 12 gram seal.
I just worry about static o-rings holding pressure, it is the reason BE nightmares fail.
Perhaps taper the area in front of the orings and put a spacer that will help push the orings out, like the non-cartridge valve.
Something I've done is to shorten the threaded portion of the cartrige valve to increase the area behind the valve.
IIRC, the main issue with the nightmares was cutting the o-rings as you pushed them past the air transfer ports in the back of the gun. I think the best comparison with these would be Spyder/CCM/AKA style valves, which rely on a static oring in a groove without any taper holding them in.
i dont think im understanding this. what the extra length is doing. it seams like the limiting factor for a cartidge valve would be the area the gas has to flow through in the valve itself.
like area around the valve seal and small area inside the valve and transfer hole.
what is airgunner?
I grabbed these images from an airgun forum. They aren't adding length - those are CB9 valves - they're removing the exterior wall of the Sheridan cartridge valve to increase the total gas available when the valve opens. Stock Sheridans have tiny little chambers, and PPS even opens them up when they make their scratchbuilt guns. This is just a dead simple way of increasing volume in a cartridge valved gun.
ok thanks, im getting ready to do a regulated sheridan project. and was searching for cartridge valve mods. funny you posted this tonight.
and i came accross mads thread about his cocker valve adapter.
ill do some googling for cb9
hmm.. so by adding the second o-ring to the transfer port you could potentially open the entire air chamber up to increase air volume?
I have a scrapped project gun that I could revive and try this.. its almost a lost cause anyway so I would not be out much.
You mean how in the second photo they separate the chamber plug and valve body into two separate pieces?
Yep, that would give you way more volume, the only trick is adding extra o-ring grooves to make sure it's sealing.
russc - I was talking about this one.
Yes the o-ring that is to the left of the transfer port is essential, otherwise you get a leak down the barrel.
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