There only a few companies that produce their own uppers and lowers and then parts. The vast majority of receivers are made at only a few locations and then roll marks are put on later. If you look around a tad, you’ll find that CMT (Continential Machine and Tool) makes receivers for a bunch of companies. Regardless of the name on the side, check to see who really made it. Here is an old list:
LMT = LMT, Lauer(old), DS Arms, PWA, Eagle, Knights Armament, Barrett, Bushmaster (?)
CMT = Stag, RRA, High Standard, Noveske (old), Century (current), Global Tactical, CLE, S&W(now made in house), MGI (1st batch), Wilson Tactical, Ratworx
LAR = Grizzly, Bushmaster (L Prefix), Ameetech, (?)DPMS, CMMG, Double Star, Fulton, Spike’s Tactical, Noveske (new)
MMS = Mega, Gunsmoke, Dalphon, POF (forged), Alexander Arms, Stinger, Spike’s Tactical(old)
JVP = Double Star, LRB
Olympic = Olypmic, SGW, Tromix, Palmetto, Dalphon, Frankford, (old) Century
Superior = Superior Arms, Lauer (current)
Grenadier Precision
Sabre Defence (?)