There were several M16 magazine makers during the post-Vietnam era. There were actually just two sets of contract 30 round magazine tooling, both built by Colt. They wandered around from contractor to contractor. These contracts were usually "minority or small business set- asides." Typically what would happen is a small business would get set up with the tooling, and start to crank out a contract. Then, the contract was so lucrative that the business no longer qualified as a "small business", the contract was cancelled, and the tooling got yanked and sent on to the next contractor. Contractors included: Adventureline, Parsons Precision Products, Labelle Industries, Sanchez (DSI), Center Industries, Okay Industries, Cooper Industries, and a few others.

There are even M16 magazine collectors as there are so many different variations around. I think I have examples from every manufacturer, but they don't vary much aside from what is stamped on the floorplate.