It's a technicality, but yes, you can buy components and have him reload them for you. Especially if you're present and learning/helping. (Just be careful not to be a distraction, of course - a reloading bench should be clutter-free and distraction-free for safety). I've reloaded for other guys in this way for over a decade now.

You can also technically "rent reloading equipment" from your buddy if he'd give you access to reload your own ammo. But personally, I don't want anybody touching my reloading bench but me. I don't even let my wife run the press if I'm not watching over her (she's only been at it for 2yrs, but she's a very capable and scrutinizing reloader).