I would try both. I have used magnum primers when others said I didn't need to, which resulted in tighter groups. This was in non-magnum cartridges, .22-250, .243 and .25-06.
I think I read somewhere that Roy Weatherby had Federal make the No. 215 LMR for his cartridges which were burning over 50 gns of powder.
I use both in my 7mmRM, 26" barrel. JohnnyK.
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