FX crown setttings for different caliber .25 versus .30

[PCPair]

I shot a fx crown .25 a few days with the flow at 3 and the hammer setting at max, internal regulator at about 125 bar and shot the JSB kings 25,4 grains at about 900 fps and the JSB kings heavy at about 790.

​So with all settings at max i get a .25 speed that i would expect from a standard fx gun. But i just wonder what would these settings mean for a .30 barrel or does a .30 barrel have a different size transferport? Just wondering how this wortks

Anybody knows???

​Regards Jan Peter

 

[GQ]

The transfer port for a .30 caliber is larger like the Impact.
And 125 psi would not be enough pressure to get a 830-850 fps with a 44.95 JSB pellet.
I would go for 145 psi on the regulator.

 

[Jack.K]

Each caliber barrel has a different size transfer port on the barrel. Here are 3 different caliber Impact Barrels .30, .25 and .22. The crown has an additional transfer port dial with 3 settings which restricts air flow between the regulator side and the transfer port on the barrel.

 

[T3PRanch]

"GQ"The transfer port for a .30 caliber is larger like the Impact.
And 125 psi would not be enough pressure to get a 830-850 fps with a 44.95 JSB pellet.
I would go for 145 psi on the regulator.

145 BAR.

Thurmond

 

[PCPair]

Thanks for the replies

​I did some testing with the hammerspring presettings and was able to get the JSB kings Heavy up to a speed of max 850-860 fps by following the YouTube video instruction.. It really starts at minute 5.

In my case maxing the screw out resulted in the gun shooting higher on the 4 hamersetting than the MAX setting. Pressure about 130 bar. I do not know what causes this but i turned the screw back in so it had more play on max and this resulted in a more balanced hammersetting. MAX giving the highest velocity as you would expect.

Regards,

Jan Peter