I did a test with all my 270's a while back with 60 gr of H4831 and 130gr Barnes TSX, TTSX, Hornady 130gr GMX, and Interlock.
All the same loads and used WLR and WLRM primers. In every instance with 8 different 270's the WLRM loads shot better groups, were faster and had better chronograph numbers.
I now keep those four loads RTG in my ammo stash and whenever I happen into a new 270 I go to the range and see which one shoots the best. Almost every time I can find one load that is hunting suitable at 1" or better, sometimes two.
There was one 270 that would not shoot any of the eight loads when tested. The smallest groups were about 2.5 inches with the WLRM and some over 6". It went down the road.
So from my non scientific experience, I would certainly start with magnum primers and change to nonmagnums if I could not get satisfactory groups.
