I am getting ready to buy my son a gun to turkey hunt. I know that I want to buy an 870 youth model for him. But I noticed that Remington makes the 870 youth model in a 16 guage that is 2 3/4 only. Would it be better to buy him the 16 guage 2 3/4, or would it be better to buy a 20 guage that shoots 3". How much selection is there in ammo for a 16 guage.