The theroy goes like this. Shorter stiffer actions that wsm's utilize along with all short actions are more accurate. Also, with the shorter powder column which is closer to the primer uses burns the powder more efficiently and realizes less recoilper fps developed.

Is any of this to say long actions are not accurate? NO....but look at the cartridges that are used by the bench, and high power and other target rifle shooters and you will see the vast majority are using short action rounds. There is a reason for that.

There is a lot that goes into making a rifle accurate but also todays production rifles are more accurate than many from the past as well.

What I believe is that there is a greater margin of accuracy with a short mag than a standard long action magnum. Meaning it is easier to find a wide array of ammo that shoots well through a short mag than through a long mag.

I have a 300 wsm, and a 270 wsm, and also have a couple of 300 std win mags. It took a lot more of a process to find the loads that my std mags like while it seems most loads I try in my wsm's shoot well.

While ballistics are a science they are also a lot of theroy.