If you are referring to a Ruger, go to their website, look under customer service.
You did not provide a serial number.
1964
1965
It was manufactured in 1961.
Ruger has sn data on their web site.
Ruger's website has a sn function.
To determine the age of a Lakefield Mark II based on its serial number, you'll need to refer to specific serial number records or documentation from the manufacturer, as the age can vary widely depending on the production year. Lakefield International produced the Mark II in the late 1980s to early 1990s. If you have the serial number, you may be able to contact collectors or resources specializing in firearms for more precise information about its age.
You will have to call Colt
If the Ruger website is working, it has sn data on it.
Blue Book of Gun Values
Try proofhouse.com.
The rifle is a Mark II BAR Safari, manufactured in 1995.