Can't help you with the drilling part, but I took my NRS side rails that I wanted shortened to Home Depot. They cut them and finished the ends (reamed them????) all for free. Turned out perfect and the rubber end caps fit back on snug.
"We are all visitors to this time, this place. We are just passing through. Our purpose here is to observe, to learn, to grow, to love....and then we return home."
Australian Aboriginal Proverb