1) Muzzle Energy:
300 WSM
165 grain - 5,162 J
270 WSM
150 grain - 4,442 J
308 win
165 grain - 3,621 J
Which means that 300 WSM is roughly 15% more energy than 270 WSM and 42% more energy than 308. And 270 WSM is 22% more energy than 308.
How you "feel" it depends on everything from clothes, mass of the shooter, mass of the rifle, way of shouldering, presence of sharp spikes in the butt plate and so on. However, for same rifle, same shooter energy of a kick of 300 WSM is 42% more than 308.
2) Why you came to 270/300 wsm:
You are saying that you want sako A7 and it only comes in short mags. Ok, fair enough. But I'm assure you that you DON'T want sako A7.
What is A7? It is overpriced Tikka. Bolt is 2 lugs push feed with spring ejector - same as Tikka. Bolt has plastic in it - same as Tikka. A7 has plastic single stack 3 round magazine - same as Tikka. It has pic rail mounts - same as Tikka.
Tikka T3 light stainless MSRP - $800
A7 MSRP - $1375
You are playing premium for a label, but technically you are buying same steel for 70% more.
At the same time, if you look at Finnlight (plastic) or Gray Wolf (laminate) they are real Sako 85
Bolt is all steel, 3 lugs, (semi) controlled feed, mechanical blade ejector. Magazines are all metal 5 rounds double stack. Mounts are for rings and bases.
MSRP on grey wolf, finnlight about $1700. Which is 20% more than A7.
3) Real question is
If you don't care about technical, buy Tikka - much cheaper, any caliber you wish. If you care about technical - buy real Sako, again, in any caliber.
But first, ask yourself, do you really want to buy 70% overpriced A7 with 42% more kick energy than 308
