At last check, YTM (blackrifle.com) doesn't have any Colt parts, and doesn't know if they will be getting any ever again...
The M4 Upper is very hard to find right now for any price under $800, and if you're lucky it'll be new. In fact, any Carbine upper/barrel is hard to find- let alone those stamped with the desirable "M4".
I'm looking for a Colt Preban 16" Lightweight Small Hole Upper in Colt Tactical Black with 1x9 twist chrome lined bore or any of the major components to complete the above...
Any leads, please post here...