I had the same experience with the .375H&H as to accuracy, Steve & to the point of bullet weights of 235gr. to 300gr. all going into a big group that ran a little less than 1" x 2" or so, on centers, with individual bullet weight groups of 1/2", within the composite group.
That they were all in a group an inch wide by 2" high speaks volumes for having one sight setting for all bullet weights.
The 300's of course were lowest, with the 270's next and in between the 300's and the 235's, just as you would want/expect.

Further, I don't know if the 9.3x63 shares this close point of impact trait with different bullet weights, but my 9.3x57 did using resized 225gr, .235gr., .232gr. Norma, resized 270's and the 300's I tested in it.

It is nice to have a single sight setting for all bullet weights.

My .30/06 M70 almost does this, only 1/2" to the right & 1/2" lower with 180gr. vs. a sight setting for the 165's. It's close enough for "government" work.