An export/commercial variant of the Colt M16 rifle, the base configuration of the Model 639 included a short barrel fitted with a special sound moderator/flash hider designed to alter the report of the carbine, to make it unrecognizable to forces familiar with standard M16/AR15 family rifles; while not a true silencer, the moderator was close enough for regulatory purposes to require a second tax stamp, and on this example it has been replaced with an A4 pattern upper with a closed-bottom bird cage flash hider, "1/7" twist rate marking, bayonet lug, ribbed round handguard and a detachable rear sight/carry handle assembly. The lower has the "COLT/AR-15" logo on the left side of the magazine well over "MOD.639/CAL. 5.56MM./4790061", and the Colt Firearms Division address is stamped near the right handed "SAFE/SEMI/AUTO" selector switch. It is fitted with a checkered pistol grip and a two-position telescoping buttstock. Includes a plastic hard case. Magazine absent. Provenance: From the collection of Mitchell L. WerBell III.