My old Crossman's manual said to never exceed 6 pumps. Two pumps was good for a sting, more than that and it depended on the target and pellet as to the damage. More than 6 would damage the gun's seals.
Set up some targets, cans, paper, cardboard, etc. and experiment to sight it in and get used to what kind of power you have/number of pumps.
Just make certain of your backstop and watch out for ricochets with those BBs.
You don't want to put out your eye.
Sales dude at Dicks says 25 pumps max. That would put one hell of a lot of muscle behind a .177 cal round, so doubt I’ll ever use that.
We also bought a practice target setup with ‘catcher’ to....well, practice, zero in the sights, etc....and yes, ALWAYS with safety glasses!
We’re both gun owners and fanatics about safety; we’ll apply the same to this thing.