Seems HW have reverted to using the original valve seal on the 75 (the small white seal)
The gun originally listed as being 440 fps....(actual 400 to 420 fps) pellet dependant until about 5 years ago when the performance suddenly nose dived to about 350 fps.
Comparing early guns with newer ones i found the valve seal had changed on its inner diameter, being reduced by 2mm.
However, opening up a brand new gun over the easter period revealled the original seal spec dimensions and a 415 fps gun with JSB exact....quite a heavy dome pellet.
Its interesting that the 75 article in the latest Shooting Sports magazine tests a brand new 75 doing 400 fps with 8.44 g pellets.
They are back to spec, outgunning the miserable FAS competitor by a full 50 to 60 fps and shading the HW40 usually running about 380 fps with most pellets.
Quite why HW did this remains a mystery but i have mailed them regarding this.