2019 Romanian AES-10B marking question

[MACH]

The marking attached is from a 2019 Romanian RPK AES-10B I was thinking about purchasing. I wanted to know if you thought it to be a proof mark, inspection mark, graffiti, or a slip of the hand ? Maybe an ex military receiver that was sanitized and reused ? I have looked online and see some WASR rifles with a M in about the same location. I am not sure what the M means, but at least it is an intelligible marking. I also saw an X in a circle which is close to the JPEG I attached here. I attached that JPEG and circled the faint X in Blue. The marking I am curious about is circled in red in the other JPEG. Thank you for taking a look.

 

[kozak6]

Not an ex military receiver, but a new one for import purposes. ATF has some rules about "once a full auto, always a full auto". Full auto receivers can be demilled and rewelded into "new" receivers, but that's very difficult to do with stamped receivers and not what this is.

No idea on the markings. I'd say to try AKfiles.