Looks to be one of the 'y' marked Romanian barrels.
Some believe this is a Russian stamp and it did not appear on most of the barrels.
Often bought and sold for use on a a Russian AKM kit build.
Often sold at a premium.
Dunno if any definitive proof of origin has been determined.
There has been various discussions if the 'y' mark on the Romanian barrels is slightly different than the Russian marking.
I have a Russian OEM AKM and had several AK47 T3 Russian barrels to compare.
Also a couple of the Romanian 'y' marked.
They are close in appearance., but it has been a while since I compared them.
I noted that mark on the barrel with a tag for future reference for a build or a sale.