Gladius Semi Balanced Valve - Didn't Work Out

[jarmstrong]

Only 9 days since you stated this post and you have whipped out a whole new valve without blue prints? WOW    It has to be nice to get high praise from Oldpro.  Keep on posting , this is the first time I have seen this design (Cothran style ?) I now see how it would reduce the force needed to open the valve. Hopefully when Travis gets done with Benjamin and Kral products , he might made some hatsan SS valves.

[JumboPellet]

With a name like OldPro, you better take his advice  I had to bore out the valve body up to .500 from .407 in order to accommodate the larger poppet. I just didn't feel there would be enough area for flow, so took the time to do that. I machined a new poppet with a .360 barrel, then a new seal. I ended up having to go back to peek for the seal since it was the only material I had that was over .500. I didn't realize all my delrin is 1/2" rod, not enough to machine down. The throat of the seal was bored to .296 and then hand lapped to 'somewhere around .300'.

Results?

JSB 33.95g       1100 fps
Rat Sniper 45g  990 fps

But the real deal is air usage is now down to around 7 bar per shot! Much more palatable than the 15 previously.

990 not worthy for the snipers, let's get them to 1000... Nice even number

[JumboPellet]

I found a radius tool in the chest of tooling I bought, so I rounded the corners on the U support in the valve. Then I machined a delrin plug to take up the space that the previous piston occupied on the far end of the valve. Then reamed the ports in the valve cap from .119 to .126 (as big as I could possibly go). Finally, sat down and took the time to match the regulator setting to exactly match the available spring rate of the .049 spring.

The final tale of the tape from a ~200 bar fill down to 150 bar:

BBT FN 51.2g

970
965
967
969
961
XXX <-- off reg

Rat Sniper 45g

1008
1007
1010
1006
1003
XXX <-- off reg

So 5 useable shots at those levels and that fill. If my SCBA tanks are full, I usually do a 225 bar fill, so may gain one or two more. But at these levels, I'll have to take what I get. I suspect I'm way down on the knee of the power curve (maybe bordering dump shots). Lots more air for diminishing power returns. I may eventually back it down, but want to shoot it first just to see. I feel I may be at the upper limit of this platform.

Thanks to everyone following along and to Travis for the tidbits of advice!

I would classify this a success, but one mistake I may look into is making the occlusion piston bigger. Perhaps up to .250 from the .189 it is currently. A .049 spring is noticeably lighter than a .055, but would of liked to see it down to the .040-.042 range. That will be for this winter, right now I want to get out on another shoot before the thermometer heads south for the year.

Regards,
Jeremy

[JumboPellet]

One final note on the JSBs, I don't shoot them that high. The hammer in this gun doesn't have the traditional Hatsan adjuster inside. Instead I have a SSG that extends through the trigger mount that is adjustable out the back of the rifle with a 2mm allen key. I use the SSG as a poor man's preload adjustment. If I back it all the way out, providing maximum limitation on the spring, it shoots the JSBs in the upper 900s. That might be a bit too fast, but I will have to see how it ultimately affects accuracy. If it does, a regulator adjustment would be needed to bring it back in check.