Here is a video I did discussing some of the features of the Colt 10.5″ modular upper receiver prototype that I have.
The Colt AR-15 Resource
"A site dedicated to the history of the Colt AR-15 rifles, carbines and associated items"
Here is a video I did discussing some of the features of the Colt 10.5″ modular upper receiver prototype that I have.
The Colt AR-15 Resource 