RE: What is a good youth model .270
X2 for me. And I wouldn't shy away from a single shot either. Chances are he won't get another round off in time anyway. I have never had to shoot an animal twice. And the people I have seen take more than one shot never hit what they were aiming at anyway, they were just slinging lead towards the animal.
Single shots are actually a bit safer and teach you shoot better because you know you have to make the first shot count. And when you are practicing it slows down your shot sequence.
Only my opinion though.
Paul