In the Sabot testing I have seen, accuracy was not what we would be interested for long range precision shooting. One main problem is that the Sabots drop frictional coefficent and that makes the huge case capacity even less functional to get consistant buring of these huge powder volumes.
A better round would be a 50 spotter necked down to 338 or 375. Heck for that matter, just a 338 AM or 375 AM would match that in performance.