Do we have a list of manufacturers upper receivers and their identification markings like keyholes?
Specifically I’m wondering if a aero precision slick side upper receiver (no forward assist) is legit. It has no markings on it whatsoever. I thought aero had a keyhole marking on their uppers?
The keyhole is Cerro Forge out of Va. If memory serves the square or modified A is Alcoa Forge. Though certain companies are partial to using certain forges to but their forgings, it has no bearing on which company finish machined and sold the upper receiver or upper group.
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 Alcoa Forge
A (splintered) = Anchor Harvey Aluminum
C MB is: Colt / Mueller Brass
Cardinal’s head (stylized bird head) is: Cardinal Forge
CH is: Colt Harvey Aluminum
Crosshairs w/“AR” is: ArmaLite
CK is: Colt / Kaiser Aluminum
CM is: Colt / Martin Marietta
D (stylized) 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
Keyhole is: Cerro Forge
PA is: Capco / Anchor Harvey
PM is: Capco / Martin Marietta
Square (symbol) is: Brass Aluminum
In the limited amount of Aero uppers I have dealt with, I only see forge markings on their standard AR-15 upper. For their M4E1 and slick side uppers I haven’t seen forge markings.
When you think about it, it kinda makes sense. A mil spec forging you would expect the forging company to include a marking. Once you deviate from milspec, there’s really no need to include it.