Proofhouse.com has sn data.
$800.00
50-1200 usd
Try looking at this, it may give an idea. http://biggerhammer.net/ar15/ar15serial.html Mike aka nfmMike @ ar15.com forums
Depends on condition, etc. Price range from 500-1000
100-1000 USD or so depending on specifics.
222, 223 and 9mm
If it is one of the recent Colt .22LR AR15 rifles, then the answer is no - they are completely different internally.
1977. Value depends on conditon and accessories. Range 500-1100
Colt has not offered a AR15 in 308
AR15, M16, M4, Ruger Mini 14
Made 1974 if sn reads SP33829. Value depends on condition. Range from 500-1000
Proofhouse.com has Colt sn tables. Value from 100-1000 USD dependingon condition, box, manual, accessories.