LMT MWS 16" Rifle-length gas system
I don't know if this counts as a custom build but here goes anyways.
Started its life as a LMT MWS and I installed a new receiver extension, safety, trigger, grip, trigger guard, end plate. I tapped the rear take down pin hole with a set screw, stippled some panels, and then bought an 18" LMT 5R SS barrel which I had ADCO cut/crown/rethread to 16".
I've only shot Federal 168gr GMM through it and it has exceeded my expectations. Super soft (for a .308) and shoots like a laser (sub 3/4 moa 10 shot group with 168gr Federal GMM).
Specs:
LMT MWS
16" 5R SS Barrel
KAC Sights
KAC Ambi Safety
Geissele SSA-E
Nightforce 2.5-10x24 (mildot)
http://buckjay.com/drop/lmt-mws-1.jpg
http://buckjay.com/drop/lmt-mws-2.jpg
http://buckjay.com/drop/lmt-mws-3.jpg
http://buckjay.com/drop/lmt-mws-4.jpg