Again, thanks for all of the replies!
While I appreciate the suggestion, a 20" barrel is out. I would consider a 20" if I was strictly looking for a long-range precision rifle. The best way to describe what I am looking for is to say I want easily-portable 5.56 precision. I am willing to sacrifice some precision for a lighter weight rig.
I have considered having an upper built around a Noveske 18" lightweight SS barrel. But, based on the responses and my research I think a 16" SS barrel will be ideal.
Plus, if I go with a 16" I have an excuse to build a 7.62 or .260 rem rifle for shooting past 500 yards
My choices for an upper are either a BCM SS410 16" upper, a Centurion recon upper, or a custom build by Rainier. Which would you choose and why? Any better selections for my budget?