Bill I'm guessing this rifle was a product of the "60s". Remove the action from the stock. Underneath the barrel next to the reciever, should be a 2 digit number, ie, 65 would be 1965. Also go to
www.weatherbycollectorsassociation.com, you will find this an informative site for your new acquisition. Also the I think the "P" will tell you where the rifle was manufactured, Belgium, Calif., Japan. Hope this helps, just went thru the same situation with a Mark V I inherited from family. Happy hunting!