Just finished putting this together. my first "ground up" build. although I kinda cheated in that I bought a barreled upper that already had the barrel and gas system assembled onto the upper.
Palmetto State Armory mil-spec lower
PSA Build kit w/ mil-spec GI trigger
--hand polished the sear/hammer, absolutely NO grittyness!!
Spikes mil-spec BCG w/ C-158 HPI/MPI bolt
Bravo Company upper with Hammer forged 16" barrel, mid-length gas system
Aimpoint M3 optic
Magpul flip up back up sight
Bravo Company tactical charging handle
Quad rail hand guard
Hand woven paracord sling
1911 style pistol grip with wrap around hogue rubber