As this is a UK unit it most likely have a number of so called anti tamper devices installed.
These need to be removed to be able to adjust, for instance hammer spring pressure.
The PB as a platform though no doubt has much speaking for it. Simple n rugged in short terms.
On the earlier guns it´s rather common with broken loading levers as is it with poppet stems that looks like a d*mn Z after a No of firings.
That being said though...
I pulled the plug completely on one in 25cal and the thing just simply delivers. Granted, not all that much of the stocker remains but then again OTOH it kind of is a proof of concept if nothing else.
Since it sports a regulator set to approx 160 bar on a larger plenum.
As you can see even the stock is severely lightened. Reg pressure gauge has been added as has an auxillary tank on 350cc. Runs both hard n long due.
What i´m saying is that the potential is certainly there.
To get to the anti tamper, if applied, the innards needs to be let out of the stock. It´s held in there via one single allen bolt that rides in the cutout on the stock behind the trigger.
Remove and need be take a pic n post.
It is NOT illegal for you to remove the anti tamper to meet power requirements.