Going from memory, there's a tiny little allen screw partially hidden under the trigger blade, in the little silver block. Winding out increase first...
There is a Camera Tripod I could lend you, get one of the Lads to help you into position and rest the foregrip on it, was planning to eventually make...
Aren't you technically unable to use a Pellet twice?
I get you, don't mind buying the good stuff for proper work but when it's just sending into old...