What is this marking on my AR? -Pic-

[FireStorm]

It looks like a pellet..


http://img193.exs.cx/img193/2218/marking4ub.jpg

[DMK]

I may be wrong, but I believe that's the forging mark. Basically, the symbol for the subcontractor that produced that part. Both of my carry handles(one is a Bushmaster, the other an RRA) have a cardinal's head on them.

[thelast2]

Yeah that is a proof mark which if im not mistaken is found on Colts AR's.
The proof mark is there to show which part manufacture or contractor made the part.

[G56]

The keyhole symbol is a foundry mark, identifying the maker of the raw forging, it has nothing to do with a proof mark. I don't recall which foundry marking that is, but it's not really important, it's the steps that come after that, machining etc, which are more important.