Threaded End caps? I get them where I live for like 14 bucks I think. Not that much difference.

Technically, I would think you could make a hybrid out of a piston valve. Put a compressor relief valve behind the piston that is above the "charge" pressure. (say 160 if it were to be copper) When the propane ignites, the pressure difference should push back the piston decreasing the pilot volume ...

why not try to make it a hybrid? Have the propane flow constant into a chamber with a burst disk that doesn't really burst but just releases the pressure at a set psi. Ive seen these in the oil field but you probably wont find a scaled down one.

Fill it up with the compressor then top it off with a hand pump. 20psi or so is a big difference

Nice pistol BTW, I like the fill tube.

Dont forget to put pressure to it so the epoxy seeps into the leaky areas.

I was backwards of that, I thought the leak was coming from the barrel and it was no big deal. Unfortunately it wasn't

Not for copper but kind of related...I used a hose clamp and welded a piece of pipe to it for my bolt handle which attaches to SDR26 pipe (couldnt get 21) The slight pinch in the pipe holds golf balls awesome yet you can still make them fall through by jarring the barrel on concrete.

I thought ...

Its a unusual pain hey! I had the same problem with my over under piston and the shaved bushing in the front of the Tee leaked. I just opened the back shot two suringe fulls of glue down there slopped it around then pressured it up and left it. No leak and extra strength from all the glue

Using calculations, which I'm sure yours will fail...

First off, where the hell do you get off telling me I dont know what Im talking about...obviously your work "on paper" is incorrect; let alone your whole theory on the forces involved that even make a piston valve work.

How do you suppose a ...

All housed in a 3" tee...piston is about say 2.75" running in a machined track with no obstructions. bumper is changeable but I only have 1/4" of working room for a bumper

Were you planning on a mechanical or electronic system to actuate you ignition? First off no matter what you do it, having a high voltage spark/ peizo igniter near any RC equipment will cause huge EMI and glitching in your servos. That aside I do have a suggestion.

Any one who is familiar with RC ...

What is the limitation on the ROF? I would assume it will still fire when you have a lower pressure but in your video it sounds like a ammo loading problem.

How do you get the air to equalize fast enough. You must have a check valve for it to be that reliable?

We are saying you need 1/4 to 1/2 of your barrel diameter (so for a 2" barrel port you would need 0.5" to 1") for a minimum of "piston travel" to give you a full volume port to maximize the air flow out of the barrel. The piston travel is how far the sealing surface (on piston) will move away from ...

Thats what I thought to but I mean there is a 1/2" ball valve wide open venting an Oringed piston that has minimal leakage and one 3/32 equalization hole.

Could be my design too. My barrel side seat has only 1/2" gap before my piston sleeve is there coming about 1/2" in covering the reservoir side ...

I had the exact same question for a while.

What I did was take a piece of 3" Sch40 pipe (3" Tee as well) and cut down the OD to go past the stop on the socket. I left a small piece about a 1/2" long the same OD as the normal pipe to stop it at the desired depth in the end of the socket. I bored ...

I agree, would have done that on mine but I had already put the hole on the side before I thought of using the front (barrel sealing) rubber for the check valve. I think thats my problem with mine, it still works though just with a bigger pilot valve.