By the serial number. Try proofhouse.com
Normally, it's on the barrel.
Call Colt
as best I can determine about 1880
Go Here...http://proofhouse.com/colt/ Regards
The date of manufacture is determined by the Colt model type and serial number. See: www.proofhouse.com/colt/index.html
With the serial number that you have provided,your Colt Model 1911 was made by Colt in the year 1918.
what model colt ??
You will have to call Colt to find out.
It tells the year of manufacture of a Colt.
You will have to call Colt
you must provide the serial number in order to determine the mfg. date.................... on any firearm.
Compare against a known original, pictures of of one or appraised by a professional who deals with Colt's.