Who made a 16 gauge Eastern Arms shotgun and when?

Answer

Eastern Arms was a trade name of Sears Roebuck. From about 1905 - 1915 it would probably have been made by Meriden Firearms, a company owned by Sears. Later guns were probably made by J. Stevens Arms. But since the low bid got the contract, some were made by Crescent, Iver Johnson, and others.

Sears sold guns under the Eastern Arms name after WWII as well. Eastern Arms guns made by Stevens were marked 101.7. Any guns sold by Sears that were made by Marlin were marked 103.xx with numbers after the decimal indicating a specific model.