CLICK HERE to see the Colt SP1 serial numbers from the year 1963 through the year 1982.
Hat tip to: retroblackrifle.com
CLICK HERE for the history of the M16 rifle.
NOTE: Over the years, "AR-15" (AKA AR15) has become the common-usage name of the semi-auto civilian version of the M16. When Eugene Stoner of ArmaLite created the select-fire full-auto / semi-auto military rifle, he designated it the AR-15. COLT bought the rights for the original AR-15 from ArmaLite and it was rebranded the M16 by the military. AR stands for ARMALITE; it does not stand for AUTOMATIC RIFLE. Colloquially, AR has taken on a patriotic connotation as standing for America's Rifle; so be it.
I believe Colt still owns the marketing rights of branding any rifle as an AR-15.
Mar 11, 2019 ADDENDUM: As of now, I still can find little information on how many AR15 style rifles are in the hands of American citizens.
Jan 31, 2020 CLICK HERE FOR MORE INFO
Nov 19, 2020 20-Million according to ---> https://www.thefirearmblog.com/blog/2020/11/19/20-million-modern-sporting-rifles/?utm_source=rss&utm_medium=rss&utm_campaign=rss&utm_source=rss&utm_medium=rss&utm_campaign=20-million-modern-sporting-rifles