I've been doing load development for a 25-06 to use on chucks. Most accurate bullets have been the Berger VLDs. The powder/primer combination that delivers SD in the single digits, like 2fps, is RL-23 over CCI-200 primers. I have very few of the CCI-200 but have a brick of the CCI-250s so I've tried them and the results are not good. Same powder will not give low SD with the 250 primers!?!? I've tried to vary the powder charge and seating depth with no joy. So, yes, Magnum primers will make a difference in how your loads shoot. With the right powder I'm sure they will be fine. I use the CCI-450 primers in one of my 223s and get excellent results from them. Load some up and run them over a chronograph to verify and compare with your standard loads and primers. Who knows? You may get lucky.