Looks like a 5.56 variant . I had trouble with a few of those clean . Lol. I've thrown dirt and sand in a few of my aks. Did not have an issue.
It is, and if you look at the comments, that is the exact same thing every body else said. So they went back and did it again with a 7.62 and had the same results. If you search their videos you will find it. 5.56 or 7.62, doesn't matter, they have the same trigger control group and the same gaping hole in the side of the receiver letting crap in to much it up.