There is markings on the the top of the trunion , left side : a squiggly T in front , then a V with the lines extending a bit further at the V .
Then a small O with little tick marks every 90 degrees , and last a triangle .
There is a 215 on top og the safety through pin . There is a small 7 right above the bayo lug , left side .
Bottom of piston housing there is FO 2705 , back of top cover says FO 3674 .
755 on left side of take down button .
On the bolt carrier right side is a V then very faint is 71 Z 4374 .
On the bottom of carrier is F then a little O then a sideways V .
On the bolt right behind a locking lug is what looks like an asterisk then KO 804 and a small triangle.
Thats all the markings that I can see .