RE: Best dies for .257 Wby mag?
OldTargetShooter,
The best dies are specialty dies like the Wilson dies and the next choice would be Forster dies. If you want the best these are what you are after. If you want good then any of the major brands will work: Redding, RCBS, and others. If you are price conscious then Lee brand fits that bill.
There are other custom dies that will be in the same league as Wilson.
PaulS