TargetTalk

I have a FWB P40 air pistol for 10 years.
never before has failed
for a while I could feel speed varying
When I put 180 bar pressures in cylinder, the pellet speed drops dramatically about 300 fps and sounds very slowly, when the pressure in the cylinder is less than 100 bar, speed is normalized to 480 fps.
in my country there is no compressed air gunsmith certificate, must make the arrangements myself, consult the FWB factory and told me to be the pressure regulator.
disarmament with utmost care that piece, find a suspect O-ring and change it.
the problem persists, any help?..................

My first advice would be to do what the factory told you. Get a new pressure regulator.
Second, since your gun is 10 years old, I would replace all of the o-rings.
Third, while you have the gun apart to replace the o-rings, give the inside a good clean and just a bit of oil on the moving parts.

These guns are quite simple, and even if they look complicated at first, once you start to disassemble you quickly understand how they work.
Go slow, don't force any part loose, and take pictures with your phone or digital camera to help you get it back together.

Once finished check and adjust the velocity if need be.

Hope this helps

If you had the pressure regulator apart, recheck to see if any parts needs to be replaced or cleaned. Use FWB special grease sparingly to lubricate the internal o-rings and parts.