1 - find serial number on weapon 2- find book with serial number data for weapon you have.
Just by the serial number, no.
With just the serial number, nothing.
You find a published list of serial numbers for the maker.
Look on the butt.
Not really
You can't value anything with just a serial number. Who made it? What condition is it in? Is it a hand gun or a long gun?
Impossible to value with just the serial number.
No serial number provided; no way to answer.
Try Proofhouse.com
Look up the serial number.
Impossible to answer without the serial number
Impossible to value with only the serial number and no other information.