Besides the serial number,I would need to know the model name or number and the maker of the shotgun in question to give you a correct answer to your question.
Your serial number indicates that your Browning shotgun was made in the year 1955.
with a serial number of E261611
The serial number to a browning shotgun made in the year 1989 will have the letters PN found some where in the serial number.
Your serial number indicates that your Ithaca shotgun was made in the year 1920.
With the serial number that you have provided,your Winchester model 12 shotgun was made in the year 1956.
Your serial number indicates that your Winchester model 1897 shotgun was made in the year 1913.
Your Winchester model 12 shotgun was made in the year 1934,with the serial number that you have provided.
Your serial number indicates that your shotgun was made in the year 1955.
Your Browning auto-5 shotgun with the prefix of 70s to the serial number identifies that your shotgun was made in Belgium for Browning in the year 1970.
with the serial number that you have supplied,your Winchester model 12 shotgun was made in the year 1921.
If you have a common shotgun made before 1968, there probably is no serial number to look up. If the serial number is not on the receiver some where; i.e., water table, side, bottom, somewhere; then it doesn't have one & that is as far as you can take the serial number of a shotgun made before 1968.
Your serial number indicates that your Winchester model 12 shotgun was made in the year 1913.