Classic416 (or should I say, Classic375!

):
If you don't reload, the answer is easy. You made the right choice. If you wish to get into reloading later on, just screw in a .416 Remington barrel and get on with it. A .416 Rigby barrel will also work fine in that action, but may need work on the magazine and feed-rails, or a replacement mag box. Others here will know...

Welcome to the forum, BTW.

Also, when you get time, please update your personal profile to show everyone you're a proud banana-bender! (I used to be one once.....

)