Looking at it logicly, since you already have a .270 and a 30-06 the 257 and 300 are not going to really spread out the caliber firearms much at all. They are also not going to do anything better or worse that the two you already have will do.

If I were inyour shoes I would opt for a true varmint rifle in .223 or .22-250 or a rifle that is .338 or .358 such as 338 win mag, 338-06, 35 Whelen, 350 Rem. mag. To spread out your battery a little bit and not keep clumping all of your rifles in the same range of cartridges.

Another option would be a big bore lever rifle. Something like a 444 Marlin, 45-70, or 450 Marlin.



Having said that, sometimes you just want what you want. The .257 and 300 WSM are super fine cartridges.