Look at the action and the bolt. If they show wear, you might consider have a gunsmith look at it, preferably one who has a scope, but unless you know the history of the rifle, I think a 257 Wby might tend to get sold when the barrel is shot out, or close to it, because of short barrel life in that caliber; so going in, I look at it as if I am acquiring an action for a project and price it accordingly. If a seller isn't reasonable, it never cost me anything to pass on the purchase.
New rifles are inexpensive these days, and a new Vanguard is now available in that caliber for the cost of a new barrel.
TC