Well, the 300 Win mag just might be easier. I don't know what kind of bottom metal or followers that Weatherby puts on the "standard" magnum rifles, but you could just rechamber the Win Mag. Case head size should be the same, the Wby rechamber will clean up the Win mag. Only changes beside the rechamber would be if the magazine box is long enough, bottom metal, and follower. Just might be that these are already long enough (except for the follower, I doubt it is) and Weatherby just put a spacer in the magazine well for the shorter Win Mag. I don't know this for a fact, but it is my suspicion. You can get the follower from Wby, but just giving them a phone call and telling them your cc#.