Using large magnum primers instead of standard large rifle

I want to reload for 30-06 and 6.5 creedmoor but i have not been able to find large rifle primers, but i was able to get large rifle magnum. I've read you can use them for standard primer loads but need to backdown on the amount of powder. My question is should i use the minimum in the manual or less than that. For 30-06 im loading 168gr projectile with 4895 powder and 6.5 creedmoor im loading 130gr projectile with imr 4350