Cerro Forge, used by just about everyone at one time or another.
Posted: 12/20/2006 9:33:47 PM EDT
[#2]
There's another one of those Cerro Forge keyhole marks with three vertical dots in it... weird. Last one I saw was on a Bushmaster upper, but everybody uses Cerro (CMT, RRA, DPMS, Bushmaster, and more). The barrel stamping is the best way to ID a complete upper.