My police department just received a US government owned M16A1. To me, it appears to be of very early manufacture. The lower receiver is marked "Colt", "AR15" and just below that it is marked "M16". It appears to me to be parkerized. It has no forward assist or mag-release fence. It has a triangle foregrip and an early pistol grip. Also, the bolt carrier appears to be chrome-plated. I suspect the flash hider to be a replacement; it is not the early, three pronged version. Anyone care to ballpark a manufacturing date?