I bought my son a Springfield Savage 20ga pump for pheasant season. Being a small guy the stock is too long for him and I'll need to shorten it. Any tips or suggestions for determining the proper length, method etc? Is is feasable to save the cut-off piece and replace it when he gets bigger? I will probably replace the recoil pad with a slip on type, but what's the method for fitting the origional one to the stock and making it look good?