Splintered A is: Anchor Harvey
Key Hole is: Cerro Forge
F keyhole is: FNMI / Cerro Forge
Offset Square is: Brass Aluminum Forging
LMT is: No Forge Marks, but marked LMT or L is: LMT
AF is: Alcoa Forge
C AF is: Colt Alco Forge
C MB is: Colt / Mueller Brass
? is: Cardinal Forge "Not sure what their design is?
CH is: Colt Harvey Aluminum
Crosshairs w/"AR" is: ArmaLite
CK is: Colt / Kaiser Aluminum
CM is: Colt / Martin Marietta
D is: Diemaco
DK is: Diemaco / Kaiser Aluminum
E is: Emco
EK is: EMCO/Kaiser
E MB is: EMCO/Mueller Brass
FA is: FNMI / Anchor Harvey
FK is: FNMI / Kaiser Aluminum
FM is: FN/Martin Marietta
FMB is: FNMI / Mueller Brass
LK is: LAR / Kaiser Aluminum
LM is: LAR / Martin Marietta
M "diamond" is: Mueller Industries
PA is: Capco / Anchor Harvey
PM is: Capco / Martin Marietta
Here is a list of most if not all of the contractors that make lowers for the military and public consumption. this link has a forging mark and KNS pin
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