Colt's new catalog lists a rifle called the 1960 AR-15 and says that they introduced the semi-auto prior to the M-16, and uses AR-15 in their description. Although my 1963 smooth sided Colt AR-15 is listed as the model SP-1.

I believe in the matter of being technically correct, you get the nod. Must not be many Armalite AR-15 sold, since they too have changed their desination to M-15.

I thought though that Colt purchased the rights to the AR-15 back in the day, and that Colt holds the trademark. Colt uses a different designation, model numbers, for their rifle now.

Certainly nothing to argue though, since there are many, if any "AR-15" rifles sold these days.