The unfortunate thing about this hobby is that there is always someone out there looking for an opportunity to rip you off through a counterfeit product or misrepresentation of product. The depend on the new collectors that have not had the opportunity to learn what legitimate products look like to find their sales.
The claimed ‘Colt 40-Round’ AR-15 magazine shown here was auctioned on Gun Broker with an ending date of 18 May 2020. It had a starting price of .99 cents and, after 43 bids, closed at $178.00. The seller stated that it was a pre-ban magazine that just sat in his safe. Here is the auctioned item…
Through consultation with many other educated collectors and some former Colt employees, the consensus is that the magazine above is not a legitimate Colt product but probably a USA magazine with a fake label. Below is the USA magazine product:
If you look at the labels on the toe of the magazine in the packages, they are exactly the same. Colt never marketed magazines from USA.
I hope you find this comparison informative.