You said it was chambered for short and long, long case and LR case is the same. A LR will chamber, may force the bullet a 'lil deeper which may raise pressure and yes it was made when 22 ammo was probably much milder, and you never know what a kid will try no matter what he is told!
PS: A 'long' is a LR case with a 22 short bullet, very inaccurate and useless round.