Things You'll Need
Instructions
Clean your gun up as much as possible. Removing rust, dirt and grime helps clear up identifying marks. Sometimes wiping the gun with a clean rag will help, while other times the gun needs an application of gun oil and fine steel wool.
Look for the brand of your gun. That is marked somewhere on the gun, and it identifies the manufacturer.
Look for other identifying marks, such as a serial number, a proof mark, or any other intentional indentations. Proof marks around the trigger indicate a foreign-made gun, because the United States doesn't have an inspection system.
Open the website for the brand of the gun, if the brand still exists. Look through its database for the type of gun you have. Read through the information for any other identifying marks or serial number lots that will tell you when the gun was made.
Go to a gun store or a gun show for information on the gun. They have catalogs that you can search through without having to purchase them. These books list brands, models and years that guns were made.