The best rifle air rifle in the world could be running short of power!

I put it through the Chrony and its only producing around 6ft/lbs, when I last tested it having replaced the springs it was running at around 8.5ft/lbs.

So either it was dieseling and is settling down or somethings wrong (piston seal maybe). I suspect the latter as 6 ft/lbs does seem low and the fps variation is very high too.

Any thoughts?

and not thoughts like 'use it to prop open the gate or hammer in tent pegs etc