I won't run anything more than the 123s (and like the 107, too) in 18" AR. I don't know if you are running this in a bolt gun or AR, but in general, the 140 is a bit heavy for the Grendel/LBC cartridge. Most barrels are 1/9 and the velocities from the Grendel are usually in the 2250 range, which won't always stabilize at long distance. It also lacks the velocity to open the bullet up on the terminal end (if you are shooting at more than paper). I suppose a long barreled bolt gun, loaded hotter (because the lapua brass will take it) might get you where you want to be. But with such a small case, if I was set on running 140s, I'd do a .260 or Creedmoor (the former being my next project).
