Seen here is a Excellent condition RARE Colt M16a1 model 621 heavy barrel transferrable machine gun . Cal. 5.56 factory made machine gun was one of the first guns of the M16 family designed as a Squad automatic weapon with a heavy barrel and a factory mounted M60 bipod for stability and long range applications  to fill the gap of a much needed sustained fire power machine gun between the M60 General purpose MG and the standard issue carry rifle. It was the NATO answer to the comm block RPK. This is a rare opportunity to own one of these guns in amazing condition  . This is the ultmate in heavy firepower  combo in the M16 family but with the push of 2  pins you can swap it out and run any size upper . Build your own M16 family system now . $40,000.00 + freight on a form 3 efile ready to go . 716 487 9065