Modded 1322 problem

[Buldawg76]

"The problem seems that almost no air wants to go into the valve after the first few pumps. and the pressure accumulating in front of the piston is pushing the piston back almost fully by itself even after i click it in place and retract a little..."

THIS sounds like the check to me.
Personally I didn't see the added efficiency in drilling the check and putting a pin it as being worth the trouble.
I would try it with a stock check and clean that valve out thoroughly. Also lube the check lightly.

I agree as I have not heard of drilling the check valve and installing a pin in it so unsure what that is supposed to accomplish. I wonder if he put to heavy of a spring inside the valve that the piston cannot overcome once it has a few pumps in it and is essentially valve locking only in the pump up mode instead of the firing mode.

Agreed he should install stock check valve and put as light of a spring in the valve as possible so that it just holds check valve closed and oil with pellgun oil. The compressed air in the valve will hold check valve closed once it has air inside the valve.

You want the valve to dump all air when fired so stronger hammer spring than valve spring so the hammer has to be cocked to pump it up.

[razvandragan]

Hello all,
I installed a lighter spring made by cutting the original hammer spring to almost half.it is now very light.It dumped all the air anyway even before that.I modded a lot of things in the valve.made a new transfer port .17" from a copper tube fitted inside a poly tube.it seals perfectly now.i teflon taped behind the oring on both valve and piston.The piston has two orings.
i made myself a chrono with 2 ir emitters and 2 receivers attached to a pc recording the impulses.
 the results now with 15.7 grain pellet.
5 pumps -406 fps
10pumps - 554
15 pumps -630
20 pumps - 667
It still seems very low for a 24" barrel
will report back after i replace the check valve with an original one.

[Rivers3Plinker]

Hello all,
I installed a lighter spring made by cutting the original hammer spring to almost half.it is now very light.It dumped all the air anyway even before that.I modded a lot of things in the valve.made a new transfer port .17" from a copper tube fitted inside a poly tube.it seals perfectly now.i teflon taped behind the oring on both valve and piston.The piston has two orings.
i made myself a chrono with 2 ir emitters and 2 receivers attached to a pc recording the impulses.
 the results now with 15.7 grain pellet.
5 pumps -406 fps
10pumps - 554
15 pumps -630
20 pumps - 667
It still seems very low for a 24" barrel
will report back after i replace the check valve with an original one.

If you're going for broke, I had very good luck with MAC1 milspec o-ring on the piston. The buna-n 70 or 90 just never held the pressure or built it as well as the MAC1 rings. At first they would work well but if I frequently pumped to 15 or so they would quickly wear out.
For some reason though, I had trouble making MAC1 work right in a brand new 1322. They are 90 duro, very hard, and can bind up in the tube if you don't have sufficient cycles on the tube I think. Installed in my long barrel 2289 which had a fair amount of shooting with Buna-n and they worked wonders. When I tried to put them in a spanking brand new 1322 I could hardly pump regardless of proper oiling.
You may also discover better pressure building with a felt oiler behind the piston instead of two o-rings.

I made similar numbers to yours with a 24 barrel 2289 using only buna-n but that was with 14.5 grain RWS domes. I did not cut threads off the valve or put a pin in the check. I think was at 660 or so at 15 pumps with stronger hammer spring, lighter valve spring, poly transfer port, and hand-ported, angle drilled valve from AC Customs. I took his valve and worked the turn in the exhaust port and opened up the port to 5/32.

What bolt are you using BTW?

[Buldawg76]

If you have not already done so you need to increase the internal volume of the valve by cutting 2 threads off the nose of the valve and then machine out around .060" off the inside of the valve just past the threads for the nose to right  as close as you can get to the poppet seat without damaging it. Then either get a hollow bolt probe or one with a thin tip that will seat the pellet just past the transfer port in the barrel so all the air hits the very rear of the pellet and does not hit it in the rear edge to start it moving so as to gain as much acceleration as possible from the air in the valve.

Then machine down the poppet stem behind the poppet head so that its diameter is .100" ( stock is .125" so remove .0125" ) for 1/4" rearward from the head to allow even smoother flow around the stem as well and good luck.

[Rivers3Plinker]

Hello!
the stock was a 1377.
i got a ft valve with piston and a 24" .22 barrel from mellon, and a brass breech with hollow probe from gma.
I drilled the check valve, angled the poppet , slightly angled the exhaust port, cut 3 threads off the valve, and increased the exhaust port to 0.157" and barrel.
I have joined because i am getting low results from it.

Based on the OP it looks like he has a good bolt and has cut the valve.
No mention of working the poppet stem behind the head though. This could be a choking point if not.

[Buldawg76]

Yea it does help with flow and if he has not opened up the inside of the valve body he is limited by the volume of air he can pressurize as well so every little bit makes a difference as the goal is to flow as much high pressure air as possible behind the pellet.

[moorepower]

15.5 fpe is low for a 1322??? Others have tested a hollow probe compared to extended and the extended gained fps.

[Rivers3Plinker]

I'm using a "V" probe in mine.
Pushes the pellet as far forward as a hollow probe style  but different otherwise.
No FPS testing on chrony yet but maybe this spring.

[Buldawg76]

I have used both and open the hollow probes up so that the hole is elongated front to rear and as wide as the transfer port which for 22 cal should be 75% of the bore or .1875" or 3/16" and I  have also modified the a stock probe with a piece of 1/16" stainless wire by drilling the center of the probe and pushing the wire in the hole so it is sticking out to seat the pellet past the transfer port and the only portion of the probe in the flow path is the wire so it pretty much unobstructed flow and that has given me the biggest gains as far as bolt probe shape goes.

By far the most gain is by opening the valve volume up as far as possible but it requires more pumps to reach the same pressures so there is always a trade off in reaching your goals