Longfeather,

What do you plan to use your DR for? That's the first and most important question and must be answered first. Then you target a caliber, then consider what ammo is more available in the caliber range of your choice.

Obviously, the .450/.400 3" is up and coming, with Hornady on the edge of making ammo available and Ruger with the No. 1. I wouldn't rule that cartridge out.

But if you are set on the two cartridges you mentioned, there's no question the .470NE is far more available than the .500/.416.

Curl