Would have said 7mm RM burt since you already have the 300 WM and being as their so close.......
Of your listed choices I'd do the 257 Wby.
I'd choose the 270 Win 1st then 25-06 just for the simple price of the shelf ammo.
Posted by: hokey97
270 win not bad kick but still power
Josh, if you're willing to rebarrel, then add the cost of that and any bolt face machining or parts replacement required. Now, if it's not a wildcat that you need to reload for, but rather a factory round plentiful off the shelves, then does it make sense to rebarrel, or just sell it and buy a factory built gun in that cal? Its one thing if you were building a 6mm BRx for sage rats at 600yds.
And don't get me wrong; I love the 270win. I was sizing shells for one just last night.
That said, if you want something to be a backup to the 300 you have now. Something to fill a gap in what you have now. Something a bit more unique that just not everyone has, the 257 Roy stands out as something that fits each billing. (I know, you said you weren't looking to fill a gap or as a backup)
But only for someone that reloads. Have you priced that stuff?
You might think about selling it and buy some reloading equipment. You have some new hand guns. You have some rifles... I don't know how much you shoot throughout the year, but if you reloaded, you can save money for everything you shoot. (yes, I know. I've preached that reloading as a hobby isn't to save money, but to create custom concoctions, but it is possible to cut a bunch of costs if you do it smartly)
-Steve