Mk 7 which is GAMO-made item is supposed to be full power.
The MK 4, 5 and 6 are capable of close to it.
But earier MK 1,2,3 are very fragile due to delicate thin stocks and anything over 9.5 ft lb is likely to wreck them.
I might not be quite correct with the info here but I think it's about right.
Cheers