Posting this on the go. There is an auction for a rare Colt 7.62x39mm India evaluation upper receiver that ends today 3 November.

If you look at the auction, the seller used some of my photos and text from my article. The upper is pricey but rare things are not often cheap. These originally sold for $1000.
Colt produced about 25 of these 7.62x39mm SOCOM barrel upper receivers as part of their submission for the India Multi-Caliber Assault Rifle (MCAR) competition. See my article here:
https://thecoltar15resource.com/india-mcar-test-upper-5-56mm/
The 7.62x39mm SOCOM barrels in these upper receivers are the only 7.62x39mm SOCOM barrels produced by Colt.
Have a great day!