This is from another forum talking about loading for the 7x64 using 280 Rem data.
"I used, mainly, reformed .280 Rem brass! I got 6 boxes of virgin brass, a rarity here in Argentina, so I used them with entirely satisfactory results. Just a pass by the 7x64 die, trim the slightly longer neck of the .280 and use it as an original 7x64 brass!
I also used virgin or once fired and annealed .30-06 cases. Also, just a pass througt the 7x64 die, load it and go hunting or shooting. Those "7x64/30-06" came from the die with a kind of a double shoulder. But nothing to worry about. After firing them with a 7x64 normal or maximum safe loads, they came perfectly "ironed" to a standard 7x64 case shape."