Yeah, my method of choice at the lake, more quiet. Thing is the accuracy is short-range...mine is an old Daisy pump...I think max is 10 pumps but heard not good for cylinder to always max up to that, not sure if true or not but I usually go 7-9...and farther out there is a definite drop to factor in...but inside 10 yards pretty stable which is common tree-rat range...usually go longer when higher in a tree and shooting up, while not the most comfortable there is less lateral movement. If I am able to obtain employment in the area and live up there permanently I'll be a resident and fishing and small game licenses cheaper...and the latter will see my .22's get more of a workout.
Sometimes when bored I'll draw rings on a paper plate and stick it on a tree and plink away, good way to judge drop and wind. And as you say, BB's are cheap and I got lots laying around. And BB's seem to have better velocity and penetration than the lead pellets, not enough oomph...probably work better in a higher FPS CO2 system.