Depending on the part, try Numrich (gunpartscorp) website, or try Mossberg- I think your rifle is a Mossberg 800.
Mid 1960s
1:16
Made for Wsetern Auto Stores by Mossberg, it is their Model 800C. Nice rifle.
It is a rifle, 100-300 or so
Your rifle is a Mossberg 800A. Some parts may be available from Mossberg, some are available for gunpartscorp thru their website, and some may be available thru havlinsales at their website. Good luck!
late 40s to late 60s or so