The .300 Win Mag will also work in a pinch in a .300 Weatherby, although the case is worthless afterward. I tried this a couple decades ago just for grins in a Ruger #1 and it worked just fine. No chronograph data; expect it would lose quite a bit. Accuracy was not great but not as bad as I had expected (quite a jump from neck to lands).
So the 300 win mag cartridge IS good for something....I'll be damned
