I was told by the factorygurus that pumping a ram up too far in a vain attempt to increase output can have the opposite effect and lead to a burnt out piston seal. 'A sort of anti-tamper device' was the wry comment.
I found this out after having bought a s/h Fenman at auction ... on getting home I found it very hard to cock and its output (.177) was around 5ft lbs.Diagnosis was that the previous owner had pumped it up too high.
It was fitted with a new seal, pressure adjusted and now runs sweetly, and very accurately, at c 10.3 with JSB Exact.
should have bought a .22,i did my homework and am now glad i bought the bigger caliber as the pellets are easier to handle too.plus the .22 makes nice big holes in things
aa s400k.177(tweaky regged) mtc mamba 3-12x44..theoben evo .22 mtc mamba lite 3-12x44..cp88 4"..s&w 4"