First, buy him a good reloading book from one of the bullet manufacturers (Nosler, Hornady, Sierra, etc.) and have him READ about rifle reloading. He will need the book anyway to develop safe loads.
He will need at a minimum a press, dies, powder scales, Powder (H-322, Varget, H-4895, etc.),Bullets (I'd suggest 40-58 gr. bullets but depending on barrel twist others will work), and a powder funnel. A good powder measue is handy for faster reloading but can come later if someone wanted to give him a birthday present or such.
I have a set of 223 RCBS neck sizing and seater dies I'll send him for the cost of postage. He'll need to buy a full length sizing die also.
PM me if I can help.
Dave Burton