Lower: Colt 6920 M4
Upper: Colt A3 with M4 feed ramps
Barrel: LaRue Stealth 12.5" 1:8 M4 feed ramps, Lo-pro gas block w. A2 FS
Handguard: La Rue 9" FF Quad Handguard
Buffer Tube: Colt/Mil Spec V seven makes a light weight mil spec buffer tube
Buttstock: Magpul CTR but i just switched to a M&A CAR stock
Grip: Magpul K is light weight and good angle for a SBR
Triggerguard: Magpul
Optics: Aimpoint T2 Micro w. 3x Magnifier (feel free to suggest replacement) I prefer Eotech
Light: Anything surefire
BUIS Set: Troy, But the Spikes Tactical mirco seem cool
Forward Acc: IR laser if you do NV otherwise no need for anything.
Sling: Anything single point QD
Sling Mounts: QD end plate
Parts Upgrade: Check out V Seven, they make a ton of light weight parts. You can buy them cheaper at vertexops.com
Accessories: Rail covers as the barrel and guard get hot, unless you plan to wear gloves all the time