AR9 - shotgun
AR17 - shotgun
AR22 - blank firing device
AR24 - handgun
And before Mr. Westrom sold ArmaLite to the current ownership, the official ArmaLite website noted repeatedly:
"AR Stands For ArmaLite: Accept No Substitutes."
If AR ever meant "Armalite Rifle," it ceased to have that meaning when the AR9 shotgun was developed, a long, long time ago...
you should add the AR-7 .22 cal survival rifle.