I did some testing years ago...
Benchrest primers, magnum primers and standard LRP's with .300 Weatherby, .300WM, .338WM and my 30-338. Although I didn't see as much variation in muzzle velocities with the shorter cases, extreme deviation was noticable with standard primers touching off 4064, RL22 and 4350 for the larger capacity cartridges. Accuracy didn't seem to suffer much from the sporting rifles I was shooting. Only two of them were capable of 1moa anyway. Still, having read your other threads about long range shooting, I'll pass on my experiences saying that you don't need to run the same tests. Don't waste your time using standard primers with the large capacity cartridges. They'll all go boom for sure, but like Mal said, "There's a lot of powder in those cases".
-Steve