This may help, if you use a bit of understanding and mechanical sympathy.
The Daisy 7x7s work on the same principle and with them, if the gun is uncocked and the charging/cocking lever is cycled without actually pumping, the piston will touch the end of the cylinder with the lever 3/4" to 1 1/4" from it's closed position.
ie. it goes up to 1 1/4" "over centre" and in practice, cocks with a slight final clunk.
Sorry for the description, but if you have already used the gun a little, you will understand what I am trying to get across.
Walther CP-2 Match, FAS 604 & Tau 7 target pistols, Smith & Wesson 6" & 4" co2 pistol, Crosman 1377,
Baikal IZH 53 pistol, Gamo CFX Royal,177, Umarex SA-10 CO2 pistol.