ronn nailed it.shotguns are the same too.i remember watching a show by the Army shooting team and they said something like keep your eyes closed and shoulder your weapon then open your eyes .your sights should be in alignment to your eye.if not the fit is off and you can shim the stock.If your using your youth guns im sure they can add some length to it by adding recoil pads and shims.Im no expert on the subject.welcome to the site by the way.
Now therefore take, I pray thee, thy weapons, thy quiver and thy bow, and go out to the field, and take me some venison.
Genesis 27:3 "The thinking deer hunter should mature through three phases during his hunting life. First phase, "I need to kill a deer." Second phase, I want to harvest a nice deer. And last phase, we must manage this resource so our children and their children can experience the grand tradition of good deer hunting." - Jim Slinsky