OK guys heres one for you. In a 6PPC when using a slower powder like H4895 great success has been reported by opening up the flash holes. This is a good combo, and has a few wins behind it. Why don't they use a magnum primer with the slower powder like the 6mm Br guys?

Now when shooting the 6mm Br, most times people load slower powders like Varget (Which is close in burn rate to H4895.) Why don't they open up the flash holes, like the PPC guys? Many have reported great success with 450 CCI magnum primers or the Remington 7 1/2 which my understanding is it is also a magnum primer, could this be to accommodate the small flash holes?

Am I missing something here?