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
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 ...
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
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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