Just a thought here about wanting to stay with factory ammo. If you truly want long range accuracy, no sniper uses factory ammo; it's all hand loaded. The exact weight of powder in every round (I'm talking plus or minus one speck of powder) is what gives you consistent FPS which translates to trajectory. My hand loads usually have a 10 FPS max spread with some repeat exact fps vs sometimes 80 fps with premier factory stuff, out of ten shots. At 100 yards the hand loads hit exactly in a horizontal line while the factory stuff printed up and down on the target.