I've found the same thing with switching the sabots that came with the 300 gr SW bullets to the Harvester CR sabots. I reported this a couple months ago. And my results were even more dramatic than yours. Of course you didn't switch brands only styles and still got a significant improvement.
There are a lot of people out there that think all you do is throw a max charge down the barrel, seat the bullet, prime and shoot. I've found that each and every rifle is different and likes different combinations of bullet, sabot, powder, charge, etc to get the most out of it. Even between two rifles of the same mode.
Good report - and good hunting/shooting.