I have a number of Colt 20 round magazines. These are highly sought after by collectors. They are Army and late Air Force contract 20 round. Circa 1969 to 1971. Dull alloy followers. Marked Colt Firearm Division" w/pony and "5.56 MM" on floorplate.
I got these back in the 90's when Fort Hood was getting rid of old stock.
The 3rd photo shows the difference between the older and the newer mags. The newer is on the bottom.
$75.00each. You get to choose from the remaining mags.