Micky,

You need to fire form many chamberings, like the Ackley Imp chamberings. The early Weatherby rounds had to be fire formed...375 in particular, from firing a standard 375 H&H. The habit of shooting something like a 458 Win in a 458 Lott chamber is different, as it can erode the chamber somewhat.

It is no problem to fire a 35 Whalen in an Ackley Imp chamber, but the problems start when someone trys to fire the same round in something like a Brown Whalen.