You should look into build a FAL like myself. More work then slapping a AR together, but I think it's going to be worth it. I'm going to order a AR lower just to have around for when I feel like making one. I got to check out Ban's when he put his together, super light and fast, but the FAL is just mean.

If you're looking into building a AR, many of the different receivers are made from the same factory, just different logos.

This list is about 4-5 years old, but gives you and idea:

-Lewis Machine & Tool
LMT
Lauer
DS Arms
PWA
Eagle
Armalite
Knights Armament
Barrett

-Continental Machine Tool
Stag
Rock River Arms
High Standard
Noveske
Colt
Century (New)
Global Tactical
CLE
S&W
MGI
Wilson Tactical
Grenadier Precision??


-LAR Manufacturing
LAR
Bushmaster
Ameetec
DPMS
CMMG
Double Star
Fulton Armory
Spike's Tactical

-JVP
Double Star
LRB
Charles Daly

-Mega Machine Shop
Mega
GSE
Dalphon
POF
Alexander Arms

-Olympic
Olympic
SGW
Tromix
Palmetto
Dalphon
Frankford
Century (Old)

-Sun Devil
Sun Devil forged billet receivers

-Superior
Superior Arms
Lauer (New)

http://www.calguns.net/calgunforum/showthread.php?t=50947