I prefer Hornady over Bertram as they are more consistent ito case volume and weight, but to be honest, in a double it is not that important.
In the .450-400 a 400gr Woodleigh at 2100-2150 should do the trick in front of a Fed215 and 75-76gr of H4350 or 80-82gr of H4831. As long as it regulates well I wouldn’t chase more velocity.
Most answers to loading for the doubles are in these two books.
