I have an 18" Armalite that's been sitting in my safe for years, poor thing really needs some love. I've had it for so long they no longer even make this model. It's got an 18" nitride coated 416R stainless barrel, 1/8 twist and .223 Wylde chamber. I'm thinking it would make a nice base for a DMR build. It has a pretty decent two stage trigger already but it needs some good glass. What have you used on your longer range ARs? What would be a good magnification range? 2.5-10x? 3-12x? 4-16x? Does more than 10x even really make sense for 5.56? What say INGO?