The only difference between the two stocks is the diameter of the barrel channel inletting.
A magnum barreled action will have a larger diameter barrel so the stock will be inletted for this. It will work just fine for a non magnum barrel contour you will just have a little extra free float around the barrel.
If you use a non magnum stock on a magnum barreled action you will probably have to do a little inletting to the barrel channel to get it to fit properly.