ba_50: I don't think that's really a problem. I have the same rifle, circa 1946, and did not have that problem with the stock the rifle came with but what you describe is not a problem (at least to me..); it's a good tight fit and that is what you want.
Are you sure it is the magazine box that is binding and not the front lug?? Is your stock bedded?? Is this rifle new to you??