AGT URAGAN 2 .... what learned these past days

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Motorhead

Motorhead

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Nov 1, 2018
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Customers gun, a COMPACT in .177 caliber.

MASSIVE Air Hog !!! Horrible efficiency even tho it came set up to shoot JSB 8.4 @ 900 fps it sucks down the air at 40+ psi per shot.
Under the hood of cosmetic covers a very unique design being somewhat along FX maverick design lines. That being a forward trigger group & cocking mechanics & bottle mount, a BIG plenum screwing into both forward trigger and rear valving / hammer assembly. Barrel straddled over the top anchored securely to both.

Being this gun came to me with a BIG complaint of Low shot count and somewhat noisy for the power output ... We head INSIDE and take a look around :unsure:
Before going in had already figured I would be finding similar traits to other CZ manufactured pups/rifles where multi caliber choices are offered. ( Krickets, Taipans etc .. )
Yup 1 chassis and set of guts for all calibers it appears is the case here too. Barrel caliber / length & Bottle size with related parts appear to be the differences.

* Transfer path from valve to barrel a massive .230"
* Plenum is huge and all passages within moving air from bottle to valve is unrestricted !
* Super small & light hammer, short and fairly light spring ... HUH, somethings suspect ?
* Balanced valve !!! Following JSAR developed architecture ( see posted pic )

After tearing the action apart to a degree we can address specific areas came up with a few ideas ... Try them, went back in, tried some other stuff being in & out near a dozen times.

Sadly the balanced valve as built has No Lift limiting or Buffer adjustments etc ... It cracks open and fly's WIDE OPEN !! Thus why such an air hog !!

After hours of trial & error .. or not getting results wanted 😬 Figured the R&D of working with and for the JSAR team years ago during this type valves development that applying some CRUTCH fixes used back then was needed here in this guns configuration to get the valve less thirsty. for this .177 caliber application.

Placing a balance chamber rod within spring and varying its length we could mechanically limit the poppets lift to a place where valve is breathing wide open ( poppet above seat being near equal in area ) but no more !!! This also reduces chamber volume and poppet will close faster too.
Shrinking down the transfer path size from the massive .230" down to @ .140" along with other set up tricks rounded it out.

As is typical of this type balanced valve there SUPER sensitive to pressure and final speed adjusting done via reg set point. With such a large plenum here the ES is very small and seeing 3-5 fps spreads ... really solid.

All said the muzzle report is a SNAP without the LDC even mounted, screwed on it's near silent. BUT 😈 Now .... O'my gawd the PING is so obvious coming from that large thin wall plenum !!! upon shooting it's loud right against your ear & really annoying. Another day for that one, if I address it as all ?
The air use is indeed greatly reduced now, but no data collected thus far ..

Thanks for following along ...

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Do you think in .177, your getting back pressure after the valve opens, all the way untill the pellet leaves the barrel? The smaller transfer port will help that a lot. Do you think the system will work better in 22 cal? I inquired (TT) about shot count and was told the 22 got 95 shots in the 22 compact. I thought that was decent. Not liking the "ping" report. Wish AGT would take issue, like the rest of the world, with their infamous ping.
 
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jt-outta-cali said:
dang, scorching. everything I see online about uragan is raving..
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No scorch at all .... it simply is a reality that the platform was designed for larger calibers at much higher output power !!
The JSAR raptor of which I was involved with behind the scenes and then did R&D with an actual rifle in FT competition in IIRC 2019/2020 had the same issues with smaller calibers. TOO MUCH ENGINE & Not enough Car ... LOL
In small caliber guns at low to modest power there is NO NEED for a balanced valve ... this is pretty much an undisputed fact by those who have worked with these type valve systems.
 
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Ricochet said:
Do you think in .177, your getting back pressure after the valve opens, all the way untill the pellet leaves the barrel? The smaller transfer port will help that a lot. Do you think the system will work better in 22 cal? I inquired (TT) about shot count and was told the 22 got 95 shots in the 22 compact. I thought that was decent. Not liking the "ping" report. Wish AGT would take issue, like the rest of the world, with their infamous ping.
Click to expand...
Indeed choking flow via transfer constriction keeps the valves throat pressure higher and that helps fill the balance chamber a tad quicker and get poppet to close faster.
Issue we are seeing is the RATIO of Poppet head to chamber diameter is really high ( Poppet seals at @ .315" and chamber is at .230" ) This has the valve very hard to tune because it simply Blows wide open ( yup that's what its doing ) The design on having the return spring INSIDE the chamber miens it need greater volume to allow spring to compress and not go into coil bind as poppet fly's open.

Anywho ... there are a bunch of small things one can do working with such valves .. lets call them crutches that can & will help throttle down these beastly & thirsty valve designs.


PING ...
My thoughts are it becomes more of a FREQUENCY thing, That being the SOUND the poppet creates in the open/ close cycle.
If the valves dwell is Long the sound signature is more like that of a quick breath and a whooosh that is fairly quite as it moves up & back within air tube or plenum.
If valves dwell is Short it is more similar to lip smack that is a short but crisper sound and that higher frequency is what gets picked up on as a PING.

Very likely why in stock configuration this PING while subtle yet there was not really noticed, but NOW !!! wholly poop sounds like a wind chime hit with a hammer.

* I am going back into it and make a depinger ... if for no other reason than proving or disproving the device in a large plenum and not an unregulated PCP's air tube where historically used.
 
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rigbymauser said:
What can the U2 in .177 be maxed to?..
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With such a valve, large enough plenum ..... BARREL LENGTH is the first to address and then ramp up the pressure !!
Having similar type rifles ( Different brands ) using such valves in the .177 caliber, have had them running strong with good efficiency for power very close to 40 fpe with 15-16 grain pellets or slugs. That took @ 24+ inch barrel & @ 2400 psi.
Hammer weight of a OEM compact have no idea at what pressure it is no longer sufficient ? and Barrel it comes with we know is too short for such power output.

Just thoughts & no facts on this Q in this platform.
 
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vmaxpro said:
Motorhead, what size hole does agt use to close the valve? Im just curious! Also, would this be a good platform to rebarrel longer for 20gr+ slugs?
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Did not throat check it, being my intent was looking the other direction in performance :rolleyes:
Tho said looking at it & knowing poppet seals it over at .315" ... throat likely in the .220/.230 range tho a semi WAG :unsure:
 
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