AR-15 is the real name of the rifle as was designated by the original firm that designed and developed it, Armalite. AR-15 stands for Armalite Rifle model 15.
Unable to successfully market it, or the earlier 7.62mm NATO caliber AR10 version, the manufacturing rights of both were sold to the Colt company around 1960
As is well known, Colt was much more successfull in marketing the rifle to the US military. Colt later sometimes used the CAR-15 (ie Colt AR) designation instead
I've even been issued rifles that were made by two other companies (Harrington & Ricchards, and GM (the car maker) that were contracted to fill the urgent early production demands due to the needs of the Vietnam war that Colt could not handle alone
This means that "new" M4 kala rifle I got in 2007 reserve duty below was a hybrid rebuild of a new flattop upper and other parts installed over an old M16A1 lower receiver manufactured at least 40 years beforehand !
BTW, it functioned fine (I recently heard the slang term
שלפ-טופ
for this type of hybrid gun
M16 (US Airforce version without the forward assist) , XM16E1, and later M16A1, were the US military designations for the AR15 rifles. Rifles were manufactured and issued in US service with various markings on the receiver
About "Property of US Govt" on IDF M16s. I doubt that the majority of the tens of thousands of M16A1s in the inventory were actually delivered during the 73 airlift. I doubt that new 5.56 rifles were a high priority during the war
All M16s that I've been issued had this marking, including the M16A2E3s which were received brand new and are a specific model not issued to US forces. I think all IDF rifles have it due to some beurocratic reason so that the IDF can purchase them at discounted US Army contract discount rates