FX Boss underpowered

[Aldea6]

Hello,
I've just received by FX Boss .30 cal , beautifull but.....it doesn't work. I mean when I shot , there is just pressure enough to spit the pellet out of the barrel ; naked eye I can see it falling 40 yards away.
I look at the hammer spring , a bit more than 2 inches long, maybe is it an "underpowered " spring as it happens in some countries in which max power of airgun is 12 ft/lbs . I asked the seller...no answer 'till now. As I don't know this gun, I can not be sure the hammer spring is the full power type ,
but it's cleat that the valve doesn't open enough . I shot about 30 pellets with a pressure drop of only 30 bars in the tank (filled to 220 bars ).Moreover when I put the hammer spring back , I don't feel any resistance when I screw in the hammer adjuster....seens to be strange.
I hope to fix the problem myself , but if anybody has an idea to help....he'll be welcome.
Aldea6

[rkr]

IIRC these guns have a brass piece at the rear of the barrel that connects the transfer port to the barrel. In some cases it can rotate and cause a severe restriction in air path. FX often uses negative preload on hammer spring so that shouldn't be an issue.

[EricFR]

I know it's a bit late (it's more for others having that issue and looking for an answer). Can't it be the M3 20mm long shipping grub screw which is still in place? I keeps the Hammer from hiting the valve correctly. It's located in the loading slot.