One of our club members has one the valve cracked after 2 weeks use. Found the 3rd pump returning slightly less vel than the 2 when it was working ok.
This doesnt happen with non regulated versions for the U.S where the 3rd pump hits 8ftlbs but it does appear that the regulation on the 3rd pump for English and European models varies from gun to gun. This was the same with the old Sharp Innova air rifle where dumping would take place at anywhere between 4 and 8 pumps. Exhaust valving is not an exact science like a mainspring!
As regard the cracked valve Webley repaired it within 24 hours. Cannot fault the service but the valve looks iffy from where im standing. Never been a fan of pot metal....has to be the worst material ever invented really.....even cast composite plastic is better. Think of the massive strength of say the HW40 plastic composite top strap compared to say a pot metal trigger for an analogy.