Colt R6420/R6400/R6401 upper receiver. This upper was used on the Sporter II series of Colt AR-15 rifles and carbines during the mid 1980s. Large .315″ diameter front pivot pin hole. Like new condition with 1980s era factory Colt gray anodizing. This is the correct upper to restore one of these rifles. Does not have M4 feedramps as these uppers pre-date that feature.
Still has factory grease/oil on it. No scuff marks from a vice block or any other nonsense. Collector grade condition. Pictured is the actual upper you will receive.