Were do I find the Serial number

[jsalazar]

I have an old Colt FA Mfg 12 Gauge Side-by-side Shotgun 1878 HAMMER SXS.
Were do I find the Serial number.

 

[jmr40]

It may not have one. Prior to 1968 guns were not required to have them. Most had them but some did not.

 

[jsalazar]

Thank You. now my next step is how and if there is a way to find the history of this shotgun and the value.
Thanks