RE: Spine???????
Youth bows or short draw length bows for women would use the 500's. They definitely still fill a purpose.
The best thing you can do with those arrows is to start calling around and find out who does archery classes for children and donate the 500's. They'll cut them down and use them.
That way they do not go to waste and at the same time you are helping a child get into the sport by supporting your community.
What neck of the woods in MD are you in?