Both are great rounds & it really boils down to personal preference for the round or preference for a particular rifle.

I've killed elk & moose both with the 270 & it ain't even a marginal caliber for either, IMO.

I don't like a heavy rifle when not really needed for a heavy caliber, so w/o a doubt, I'd take the 270.

Out to 500 yards, the trajectory of the 2 rounds is close enough to say no real difference, tho the energy edge certainly goes to the 300, but I know the 270 will cleanly kill elk at that range, as I've done it.

As the range passes 500 yards, the 300 becomes more attractive, it you can/plan to shoot at those ranges.

The package that the 270 generally comes in is way more attractive to me from a weight & carrying standpoint than any extra punch the 300 gives for the animals to be hunted.

MM