Need help for a problem in my air pistol LP10

[Amr Ismail]

Hi everybody

Actually I have a problem in my air pistol LP10 as the following:
Sometimes when I refill the (cylinder compressed air) then put the cylinder in the pistol, I find the pressure not good, so I investigated the problem and I found that the (screw for pressure reducing valve) has moved by himself, and this happened specially after I changed the (cylinder compressed air).
In the attached, I noted the ({O-ring 1.5*1} {code:29.7}) and the ({filter} {code: 29.13}) are not exist in my pistol.
I guess that in the absence of the O-ring and the filter, maybe the (screw for pressure reducing valve) is move when I put the (cylinder compressed air), and this result to reducing the pressure, isn't it ?

Please advise