Springer air rifles are about the best practice you can do for trigger/gun control, they are a lot harder to shoot consistently offhand then any modern centerfire only thing that comes close is a flintlock.
Have killed a ton of squirrels with various springers over the last 20 yrs or so, used to do pest control on a couple farms years ago sometimes killing a couple hundred Starlings, Pigeons and sparrows every morning.. on the hog farm the pigeons were eaten by the hogs as fast as they would hit the ground, same for the starlings I shot off the big ole sows backs while they were eating. They would eat them so quick it was just a blur.