@ 40 inches.
100-1000 depending on specifics
Proofhouse.com has Colt sn data. If not there, call Colt and they will tell you.
The Colt AR-15 is a sporter rifle
Colt has not offered a AR15 in 308
If it is one of the recent Colt .22LR AR15 rifles, then the answer is no - they are completely different internally.
By it's serial number. Go to www.proofhouse.com and under 'long rifles' listing look for AR15 Sporter
You will have to call Colt and tell them the serial number.
Call Colt and they will tell you.
Proofhouse.com. Call Colt also.
I just purchased one from a dealer in like new condition for $1,000. I believe that to be the low end of the value of this gun. Most in this condition will be higher.
The AR15 series
Proofhouse.com has Colt sn data.