Age of a Bay State shotgun?

Answer 1

I have a note in my database stating that this name was used by Harrington & Richardson on guns made between 1910 and 1940.

actually :

Bay State Arms produced firearms from the 1870's to the 1880's. Most of the shotguns were produced from 1890-1910, by a different company under the Bay State name.

The original Bay State Arms Company was taken over by Hopkins & Allen about 1888 but was still actively producing rifles until 1895, and Harrington & Richardson bought the right to the trade name in 1907. Harrington & Richardson made shotguns under this name from 1908 until 1942.