There's a whole shelf of books on firearms in your library. Or you may find information on www.savagearms.com
Blue Book of Gun Values
A person could go to DPMS firearm website to get information on firearms. It provides helpful tips in the FAQ section of the website along with contact information to get further assistance.
What information do you want? Firearms have a wide variety of uses.
In firearms, antiques are LEGALLY defined as made prior to 1899, OR muzzleloading firearms. Newer than 1899, they are old, but not antiques. My best reference is Flayderman's Guide to Antique Firearms. You may also find a dealer or collector that can share some information with you. Check for gun shows in your area.
The kind of information one can find on the website Stoeger Industries is that about firearms. Namely, Stoeger Industries is a manufacturer and importer of firearms into the United States. Besides that, they also publish books and videos about firearms, hunting and fishing.
Any good sized library will have books on firearms and how they work.
Possible places to look include the internet, the library, company website.
Contact the Cody Firearms Museum.
You can go to their website http://www.hr1871.com/.
Flayderman's Guide to Antique American Firearms
Yes, you can find information for Stevens firearms at the Savage Arms website. http://www.savagearms.com/