SW - you don't necessarily have to use the same sabots that came with the bullets. I switched the shock wave 300 gr .451" bullet sabots out with the Harvester black crush rib sabots and my groups shrunk by more than half.
I have found that consistancy is the key to accuracy and that the Harvester sabots, in all the different ones I have used are the most consistant. With others, like th SW sabots, I noticed that some load easily, some firm, and some are very tight.
Find a bullet you like and try different sabots with it.(for that size bullet). If you can't get that bullet to shoot to your satisfaction, try another using the different sabots. Also play with the powders and charges.
Sooner or later you will find something that your rifle likes.