holy fuck are you shooting them with bb's or pellets?
bb's are metal and are shot by compressed air. pellets are plastic and you cock each bullet and they're launched by a spring. bb's are a lot stronger and can probably kill a bunny. pellets are plenty strong for shooting cans and can make big dents from a long distance.
one tricky thing is how some guns gives the pellet backspin to make the range longer but it makes the pellet curve up. it's fucking bad-ass.
and don't shoot somebody with that until you've shot yourself with it at point-blank. even a pellet will draw blood (scarred my arm).