well the standard ar-15 is a colt. but now these days the most poopular are generally either DPMS or Bushmaster. the best of the Best is Barret and LWRC.
Only if there was one made for an AR-15 upper, which there isn't.
No. A standard AR15 has a buffer tube that runs inside the stock that contains the recoil spring.
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
Depends on model.
@ 40 inches.
The AR15 series