I would opt for the 18. It is not much longer. Just get a short muzzle break. Try to squeeze every bit of energy you can out of it. Just a thought.I know its all preference, but if you had to choose between LaRue or Grendel Hunter upper, which would you go with? I'm still debating 16" or 18" barrel since most my shots are between 1-200 yards but i have the ability to shoot almost 400 yards if wanted to.