Are you sure that's an M4? The stock and RIS look like the one for an HK 416. And is that an EoTech XPS3 sight behind the sight that looks like a Comp M2?
The stock doesn't 100% match any I know of, but in any case wouldn't preclude it being an M4, as collapsible stocks are swappable in 10 seconds or so. The rail system cannot be a 416's, as a delta ring is visible; it's closer to a KAC M4 or Free Float. The object behind the sight is a fixed backup iron sight like this LMT unit. In any case, the gas vent holes visible on the side of the bolt carrier group are not present on the HK416 (whose BCG is not interchangeable), as gas never enters the BCG.
The stock doesn't 100% match any I know of, but in any case wouldn't preclude it being an M4, as collapsible stocks are swappable in 10 seconds or so. The rail system cannot be a 416's, as a delta ring is visible; it's closer to a KAC M4 or Free Float. The object behind the sight is a fixed backup iron sight like this LMT unit. In any case, the gas vent holes visible on the side of the bolt carrier group are not present on the HK416 (whose BCG is not interchangeable), as gas never enters the BCG.
Interesting...Now I wonder why there's rear iron sights but no forward iron sights
