The AR-16 was developed in the late 1950s as a less manufacturing intensive option to the AR-10. It began with the AR-12, which was a prototype intended to use a stamped receiver with the Stoner DI gas system. When Armalite sold the AR-15 patents to Colt, they had to revise that design, and it became the AR-14, with a Tokarev type short stroke gas piston and a stamped receiver. Two of these rifles were originally made, both chambered for .308 with folding stocks and mostly stamped parts. They were offered for sale, but there were no buyers – by the time the AR16 was ready most countries who needed a new rifle had already chosen the FAL, H&K G3, M14, or other option. Instead, when Stoner left Armalite, Arthur Miller scaled the AR-16 down to 5.56mm, where it became the AR-18.
Thanks to the Institute of Military Technology for allowing me to have access to these, the only two existing AR-16 examples film for you! Check them out at:
http://www.instmiltech.com
Long since debunked. Stoner thought the M14 was “useless” in ordinary soldiers’ hands and talks at length here about how opposition to 5.56 was based on prejudice, politics, groundless theories and blatantly rigged tests: https://www.youtube.com/watch?v=l5jtUS1kgt8