Tuning HUMA Regulator on Diana Stormriders - not working?

[tdstegner]

I have two stormriders, a .177 and a .22, as project guns. Put HUMA regulators in both and neither is working correctly. The shot strings seems to be exactly the same as when unregulated. They start out ~920 fps, climb some to ~960, then begin a pretty uniform drop off over the next 30, or so shots. Both guns are the synthetic stock models without the gauge on the under side of the stock (so no pressure gauge block to remove). Thoughts?

 

[Motorhead]

Did you readjust the set pressure or run the adjuster down to the seat and counted rotations ?

 

[tdstegner]

I've adjusted both down to about 110 bar, but careful to not go to stops. BTW, adjusting down did not seem to have much, if any, effect.

 

[dizzums]

im no expert but distinctly remember reading something when i was researching for my bandit that an oring needs to be omitted for it to vent properly .. not sure if it applies .. just throwing it out there ..

 

[tdstegner]

Thanks. That's a thought. I'll check with the install instructions to see if I missed something.

 

[KatoKevin454]

on some Huma's you have to drill a vent hole.

 

[tdstegner]

As near as I can tell from the installation instructions, the stormrider doesn't require drilling holes.

 

[tdstegner]

As near as I can tell from the installation instructions, the stormrider doesn't require drilling holes.

 

[tdstegner]

I really need a dunce cap. When I disassembled the rifle, I noticed the o-ring on the regulator end of the plenum was missing. (probably fell off when I pulled the regulator to adjust it). With the O-ring missing, the regulator is just bypassed.