I envy you the chance to do a project like that with your grandsons!
After the guns are complete, they will then have to learn themselves how to sew leather and work cow horn...
Maybe they'll start perusing ToW for shooting goodies instead of World of Warcraft (or whatever). Of course, it'll all be a moot point when they discover cars, girls, and beer- but then we all know there's room in life for all of it!
