Crescent. H&D, Folsom, Browning, Winchester, Remington
1880s to 1940s
I can say that Browning started having shotguns made in 16 gauge in the year 1909.Winchester started having the model 12 shotguns made in 16 gauge in the year 1914.so I would surmise that the time frame of 1909-1915 would be the correct time frame for the introduction of the 16 gauge shotguns.
Ithica
Numerous companies in many countries have made single shot 12 gauge shotguns.
Remington has made many thousands of 12 gauge shotguns in dozens of different models/configurations.
It was made by Crescent Fire Arms Company @ 1900. Spencer was a trade name used by Hibbard and Spencer Bartlett on shotguns made for them by Crescent. Seldom exceed 100 USD
about 200 dollars
J. Stevens Arms Company
1920
Eatons of Canada
12 has a bigger bore.