The name "AR15" can only be used by Colt and companies which licence their product from Colt. Other manufacturers usually use some sort of variation for the sake of legality, such as DPMS with "A15", "AP4", etc., DoubleStar with "STAR 15", and so forth.
So, from that perspective, only a Colt or Colt licenced product technically qualifies as an AR15.
But, from a legal perspective (as far as so-called assault weapons ban laws go), most anything designed/patterned after the AR15 will qualify, including gas piston upper systems, receivers made from castings (such as Norinco, Hesse/Blackthorn, etc.), and different calibre rifles.
Try AR15.com Try AR15.com
If it is one of the recent Colt .22LR AR15 rifles, then the answer is no - they are completely different internally.
1959
Yes
The US Army presently uses the M4 carbine, a shorter and much modified version of the Armalite AR15.
Colt has not offered a AR15 in 308
By it's serial number. Go to www.proofhouse.com and under 'long rifles' listing look for AR15 Sporter
@ 40 inches.
Depends on model.
pof-USA hands down
Yes
Its ar15