I too am a fan of lighter weight! The primary parts to weight-watch are optics, barrel, handguard and stock. Of course, keeping accessories to a minimum helps too.
Using a BCM BFH 16" Mid Length ELW upper, I assembled this carbine which weighs 7.5 pounds unloaded (sans the WML) and is capable of near-MOA precision;
Note - the Leupold VX-R Patrol and GG&G mount weigh 17 ounces.