Tuning uragan, new huma reg, blows all the air out the pipe

[0akhonor]

Hi guys,

My .30 cal uragan, fabulous rifle, was/is having reg creep. Looong story short, I finally put the Huma Reg in I've had for a month or so. 

Set it for 150 bar- looking to move slugs at a reasonable speed & reassembled.

I did put the screw in the top of the reg, to slow the refill up and prolong the life of the reg.

Filled to 200 bar, and when I shoot it, get about 525 fps and the rest of the air in the tank flows out of the barrel. Recocking the gun stops the flow of air until I shoot again. I backed off the hammer about 4 turns and then added 10 ten turns- same result. 

Am I asking for too much from the reg at 150 bar?

 

[TMH]

I did put the screw in the top of the reg, to slow the refill up and prolong the life of the reg.

Is this how you left the installed regulator?

Maybe different in the Uragan regulator, but in the other HUMAs I have installed, the little machine screw is only inserted and used to pull the regulator out of the plenum. It is not left in during the install. ???

 

[Motorhead]

The screw in the adjustment bonnet is a flow damper and SHOULD NOT BE TIGHT. Lightly bottom out and back off 2-3 turns or run without it.



Now that said ... if you have ANY PCP that dumps air after a shot, yet stops when cocked ? TELL TAIL sign of way too high HST preload on the poppet stem for the pressure being run at with plenum collapsing really far in pressure ( Near dump shot ). The remaining pressure left in plenum is insufficient to close the poppet countering the HST present holding the poppet off seat.



*As to the low velocity my guess would be that the Regulator IS NOT adjusted at the pressure you think it is at ? .... or the regs seat is damaged allowing reg to bypass and valve is seeing FULL TANK pressure and in partial valve lock ?





*The above would with a LOW reg output would best support the low speed and air dumping you mention. A Valve lock situation would not dump air when shot.



Scott S

 

[ackc1234]

I second what Motorhead said. Either the reg is not set at 150 bar as you think or the dampener screw is restricting flow so much that it is causing the plenum chamber to fill so slowly that it is not giving enough back pressure to help the valve to seat back again. Personally I would remove the dampener screw fist and test. If you get the same results then you need to try adjusting your pressure up.

 

[elh0102]

I'm pretty sure that screw is for aiding in removing the reg only, something to grab with your pliers. 

 

[SteveKralsAround]

I made a semi-restrictor for the Huma . Brass tube 3mm dia , threaded and has a 1mm through hole , faster refill time without creep . I made some extras .

 

[0akhonor]

wow, great insight.

I'll take it apart again tonight- I know I have two full turns out on the screw : I'll take it to three turns. I'm trying to not have to refill the rifle so much, it takes a lot of volume out of the tanks just to get to 200 bar.

I'll back off the HST to the min and add more to the set point on the reg. 

Anyone want to venture the max amount the reg can safely run at? I reckon if the scale is wrong on the unit, there isn't much I can do but reach for the stars.

I learned of a cheat from an english website- rather than keep pulling the reg in and out, I marked a line on the reg and the adjustment screw for 150 bar on the tippy top of the reg. Now I can peek inside the tube, and gradually add more (or less ) to the reg's set point without pulling the unit.

@SteveKralls, I'd be interested in purchasing one of those brass inlet pipes; seems like it makes the damping fool proof. 

Thank you everyone, let me know if you hear a loud "boom" tonight....

 

[0akhonor]

last nite, backed off the hst and refilled- still leaked down the barrel after firing. Removed the reg, backed off the screw on top one more full turn for 3 turns out total, added 10 bar according to the reg markings, and reassembled. No leaks, 525 fps for 3 three shots. Added more hst and fps went down, so stopped chasing that squirrel. 

Took it back apart, started with the reg adjustment all the way in and advanced it to the 150 bar marking. Just in case I had wound in a few extra turns during the past month . I've had problems with breech blow by last month and worked solely on that issue (new breach oring, moving the barrel closer to the mag-had it minimized, but now the blow by is re-occurring- I'll work on the reg now and return to the breach later)

Reassembled, 425 fps still and leaking after each shot. I have the hst back out precariously far, but still leaked. Very little sound when leaking, and the firing sound was more of a click than a pop. Thinking I'll need to add to the hst, and need more reg pressure, so the hammer actually pops the seal open.

George, the puppy, had had enough of my private time, so I wrapped it up and will try again tonight. 

Was going to go one full turn on the adjustment wheel and then to 150 bar, unless someone wants to talk me down.

Nothing negative to say about the HUMA product itself, it's robust and well made. Thanks for listening!

 

[ctshooter]

This is interesting. Second messed up Huma Uragan reg this week. My Huma reg that I installed in my .22 Compact was also definitely not putting the pressure on the scale. I wonder if there is a bad batch out there. I was getting wild fps readings all over the place and output pressure was changing with input pressure from the tank. 

 

[KatoKevin454]

remove the screw from the regulator and see if that solves the problem, sounds like it's restricting to much air.