Dphillips, I too originally thought the .400 H&H was using a .411 bullet but this article clearly states it's .416 and that too could be a typo error.....anyway you cut the cake it's a .416 Remington with a different headstamp.

The .465 is totally new to me and the case used is not mentioned in this article. I just visited their website and see that they have guns for sale in both chamberings but no further info on the cartridges.

Any idea where I can find the price of Ammo?