Thank you to Lyric1 for finding me the info for this skin.
This M16 was part of the 447th AAA Battalion, which was attached to the 28th Infantry Division from D Day until the end of the war. At some point the vehicle received a field-applied disruptive camo scheme of black over its olive drab factory paint. This scheme seems to have been designed to cover up the white stars on the front, sides and rear, although the hood star was left untouched.