I once taught a youngster how to shoot a Ruger MKII pistol by going the Barney Fife route. First there was a lot of familiarizing him with the empty pistol and dry firing, When I felt that he understood how the pistol worked, I loaded one round into the magazine and let him pull the bolt, chamber the round and then fire. When I was confident that he could handle the weapon properly, I then went to two rounds(with the second round being self loaded). Again I waited until I was confident that he could operate the weapon safely and then went to a full magazine. While a Ruger MKII would be a good choice, I would possibly also think that something like a Ruger Single Six would be a good choice to teach youngsters. That is unless buying two weapons would really strain the wallet, then I would just stick with the MKII.