RE: .257 Weatherby & IMR 4831
Not exactly. But I tried it in the .25-06 Ackley Improved with IMR 4831 last year. It grouped real well - but RL22 gave me more speed and still groupedaround 1 MOA. So far, have only tried it on antelope. Hoping to get a crack at a late season cow elk in a couple of months.