Doug, I have used all three(Fed210M,215M,and BR2) primers with Retumbo/140Berger HVLD's. While I have had good/solid loads in my rifles with all three,, I prefer the Fed210's, which have "usually" produced comparable accuracy but tighter ES in my rifles. The BR2's and 210's produce comparable velocity's with Retumbo. I have found that 215's will developer MV's that are 25-35FPS higher with the same charge weight of Retumbo, or equivalent to a .5gr charge weight to match the MV of the 210 and BR2. I like to run the 140's at 2975-3000 FPS which can be achieved with all three primers/Retumbo in a +24" barrel.