We are posting these magazines separately by manufacturer for our customers use in identifying by manufacturer.
A little history of the Colt marked 30-round magazines:
The general rule is that pre-1970 30-round Colt-made magazines are marked "CAL. .223" and that beginning around 1968 all 30-round Colt magazines were marked "CAL. 5.56MM".
The Colt early G.I. contract 30-round magazines had a green plastic follower. They were marked Colt w/pony and "5.56mm" on floorplate. Circa 1968 to 1975.
The Colt late G.I. contract 30-round had a black plastic follower. They were marked Colt w/pony and "5.56mm" on floorplate. These magazines were made from around 1975 to the present. However, after the 1994 ban on high-capacity magazines was put into law, all 30-round magazines by Colt were marked either with the date of manufacturer or "For Law Enforcement Use Only".
All of these magazines are from the late G.I. contract with Colt and are unmarked with Neither a date or the special "Law Enforcement" wording on the case.
The Baseplates are marked as follows:
The logo is the Colt prancing pony in a circle
CAL. 5.56 MM
COLT'S FIREARMS DIVISION
HARTFORD, CONN. U.S.A.
I have included multiple photos of these magazines for you to determine the condition for yourself. All of the followers slide easily to the bottom of the mag and back to the top when physically manipulated by me.