You can find information about Russell Arms Co. shotguns online at places like Gun Trader or at many local gun stores. You can also find information online at Shotgun World or Arms List.
The Bridge Gun co. shotguns were made by the Crescent Fire Arms Company. You can try for parts at: Numrich gunpartscorp.com Jack First jackfirstgun.com Bob's Gun Shop gun-parts.com
There is a lot of Information on the Baker Gun & Forging Co. They started in 1890 and made shotguns up to 1923. They made several different grades of shotguns. I suggest that you go to a book store and find a book called "2008 standard catalogue of firearms 18 edition" in it you will find several different photos of shotguns and listing of the different grades. All of them are valuable. look on page 104 for the information you are seeking.
Armory Gun Co is the trade name used by H&D Folsom Arms Co on Shotguns. Later sold to Savage Arms around 1930.
You'll probably have to find a gunsmith who can make your parts. Shotguns marked Baker Gun Co were made in Belgium or by Crescent Fire Arms, Meriden, CT, for H & D Folsom in the early 20th Century.
70-100 or so years old
Bridge Gun Co was a tradename sold through Shapleigh Hardware Co. Manufacturers included H. Pieper and Anciens Etablissment Pieper in Belgium, as well as Crescent Fire Arms, Harrington & Richardson Arms, and J. Stevens Arms.
Toledo fire arms is an old company that trades in Antique Firearms, hand guns, rifles, shotguns. They also trade in ammo, gun parts, gun safes, holsters, magazines, optics, reloading etc.
For a start, info is right here. Bridge Gun Co was a trade name used on guns made for Shapleigh Hardware Co., St. Louis, Missouri, c. 1920-1940. They were made by various manufacturers.
Crescent gun co made shotguns under the name of American gun co. The problems is "How old is the shotgun?" Old shotguns where designed to shoot black powder at a much lower barrel pressure than today's gun powder. Old shotguns may literally explode if the wrong powder is used. I suggest that you take it to a gun shop and have them examine it to tell you the condition of the rifle and what shot you can use with it.
GREEN BUG, BRIDGE GUN CO. Crescent Fire Arms Co or J. Stevens Arms & Tool Co made these for Shapleigh Hardware Co of St Louis. Shapleigh dates from 1868 (to the mid 1960's I think), Crescent from 1893 to 1930, and Stevens A&T from 1886 to 1915.
H&D Folsom Co: large distributor for shotguns made by the Crescent Co. around 1930. Now it gets confusing. Crescent used over 100 different names and manufactures to make guns. American Gun made the H&D Folsom (House Brand) Shotguns under the Crescent contract. Get a hold of "standard catalog of firearms 18th edition" go to page 350 and start reading.