If you have Youth, that when their cheek is on the stock, and their eye does not line up with the sights-cut a 4 inch piece of blue foam pipe insulation, make one cut
lenght wise, spread the insulation and put it on top of the stock were their cheek rests. It should raise their head enough so their eye will line up with the sights. I discovered
this while teaching a Boy Scout rifle merit badge class.