Many early ones may not have a serial number. If they do, it will most likely be on the side of the receiver. There is a small chance it will be inside, after you remove the barrel.
What year was riverside, 12 gauge, single shot ,model 548 made
Check the barrel and receiver
On a Riverside Arms 16 gauge shotgun, the serial number is typically located on the underside of the receiver or frame, often near the hinge or where the barrel meets the receiver. Additionally, some models may have the serial number stamped on the barrel itself, closer to the breach. It's advisable to check these areas carefully, as the exact location can vary slightly between models.
look on the breach, barrel.
Try the receiver, barrel, forend
Check the receiver and barrel
With the serial number that you provided,your Ithaca double barrel shotgun with the damascus barrels was produced in the year 1900.
Please include the model number of your Winchester shotgun to get a correct answer to your question along with the serial number.
You may have to break the shotgun down in to the barrel section and the receiver section first.Look under the barrel section on the flat just ahead of the lug for the serial number.
next to the barrel
27p
Look on the receiver and barrel.