It has already been well discussed and proven that the KR units transmit the RID when in US. The only known difference in a KR unit is the AC cords that are shipped.
He was actually hit in the chest & it ricocheted into his neck. So the guy hit him on target. Jacketed bullets are notorious for taking off faces when wearing a vest with plates inserted. Most likely he was wearing 1 of the most expensive vests...
No reason for it not to be on FCC in the US. There has been no evidence that the Korean or any other international marketed M4P's are not using FCC when in the US. The only difference I have seen is the lack of the US ac cord shipped in the KR...