It’s a Galil Ace in 5.56, the ejection port is larger than the small spot you’re looking at. The original Galil was very close to an AK, the ACE diverged quite a bit more but uses the same basic design. I don’t know enough about them to tell if it’s a civilian SA receiver or not, they’re fairly rare in the US. Definitely a boutique gun for collectors and not something that falls into the black market much. No way to tell for sure but I would guess there’s a decent chance it wasn’t sourced from the US.