https://info.publicintelligence.net/USMC-M16-MaintenanceManual.pdf
https://archive.org/details/M16IchordReport1
https://gundigest.com/gun-reviews/the-ar-16m16-the-rifle-that-was-never-supposed-to-be
https://www.theatlantic.com/magazine/archive/1981/06/m-16-a-bureaucratic-horror-story/545153/
https://www.survivalmonkey.com/threads/whats-the-difference-between-m16-and-ar-15-mechanically-legal.6240/
https://modernfirearms.net/en/assault-rifles/u-s-a-assault-rifles/m16-a1-a2-a3-a4-eng/
https://www.armyproperty.com/Equipment-Info/M16A3-A4.htm
https://www.mic.com/articles/24640/gun-control-myth-the-ar-15-is-not-actually-a-hunting-rifle