I have another thread going about a 260 IMP I built. Look for 260 Remington AI. I stand corrected on the "AI" because it is only 30 degree shoulders and JE Customs will jump on you for being not correct. I found my sweet spot is 43.5 gr under a 142 SMK. My 5 shot group was 0.38 MOA @ 100 yds. This was unfireformed Peterson brass. I'm going to start playing with seating depth on fireformed brass to see if I can tighten the groups up even more.