How much fps does it take to kill a squirrel?

Depends on where you hit it. A headshot would take around 300, temple would be less, a body shot would have to penetrate fur and skin, so 400 should do the trick. Also, how about instead of killing the squirrels, how about u buy a slingshot and shoot acorns out of it at them. You hit, they fall down, you miss, they run after the acorn.