Another vote for 210M
I tested 5 different primers, the 215Ms were slightly too hot, the 210Ms we not. My particular rifle wanted the 210Ms, E.S. was very low. Im not a fan of the Nosler 150 ABLR in the 6.5 PRC. It is my opinion the outer copper jacket on that bullet is too thin and can break down in flight IF the velocity is around 3000fps. Nosler's factory 6.5PRC ammo with that bullet runs around 2750 at the barrel, even though the factory ammo box from Nosler states 2950. I tested the heck out of them and had very lengthy talks with Noslers ballistic technician. The bullet was designed for long range expansion, so might not max out the velocity. This is just my opinion based on my experience, for what its worth.
My rifle liked
ADG brass, 59 grains N565, Berger 156, 210M, in a 20'' SAAMI barrel. 1/4 min@100yrds all day long.