I have been reloading for about a year and still have a lot to learn. I know that as you get into larger capacity cases and slower burning powders that there can be an advantage using magnum primers.

I am loading varmint rounds for the 25-06, 85g Nosler, with RL 19. Currently using CCI BR. Any thoughts if this combo is best served with std or mag primers, or is this the gray area in the middle?

Welcome to the gray area. You're right about the general use/application of magnum large rifle primers, and your load of RE19 is in that gray area. The only way to know for sure is to back the charge down a few grains, try them, and work back up to maximum. It is my understanding that BR primers are fairly stout also, and I haven't had any trouble using BR primers with ball powder, or slow burning powder of any sort, but I'm thinking .22-250, 6m/m, -06 with IMR4895, 4064, and 4350. I do however, save the magnum primers for cold weather hunting loads with compressed charges of slow burning powder...just insurance I guess.

Use mag primers for ball powders in cases larger than the '06 and in very, very cold temps. Otherwise stick with regular primers.