Calculating Free Recoil is determined mostly by total firearm weight, powder charge,velocity and bullet weight.
Whether it be a short action or long action firearm is not a part of the calculating formula, but if the short actions are lighter by a few ounces, one could argue that the short magnums have more kick
Would it be a noticeable difference, doubt it.

If you have any doubts about WSMs, check out Remington's website. If you want a 700 XCR in WSM, you're going to pay at least $40 more MSRP. I bought mine in 300 WSM last fall and they were all priced the same, but they were selling fast; mine was the last one in the store in 300 WSM. I agree with rramv10 -- with the way they're selling I don't think they'll come off the market anytime soon.

I have a .223 wssm and have had nothing but problems with it. I really like the rifle, but winchester goofed with the chrome lining they put in the barrels. They recalled my first one and the second one was almost as bad. It was very accurate out of the box but only held it's group for about 400 rounds then it went to pot. The inside of the barrel feels rough so I won't even shoot it anymore. It sure looks good in my cabinet, but sure is an expensive decoration until I decide to rebarrel or not. I'm not sure I could sell it. The short mags seem to be good rifles, but if you varmint hunt, stay away from the super short mags. Just my experience.
Hank