So far with my load development venture for my 6x45 I've tried 70gr TNT, 75 sierra hp, 80 sierra btsp and 87 horn bthp. Best groups are with the 70 tnt. Is there another bullet I should try before settling on this one? I was hoping the 75 would group better but not. I have some horn 75 hp I've not tried yet. Not looking and going off memory, I think 21 grains of IMR 4198 is what grouped best.