#1). How much you want to pay? #2). How authentic do you want to be? First is always "Gun Parts" division of Numrich. They have alot. A LOT!. Service is fairly quick and you pay for good service (if they got it). After that it becomes a "hunt." SARCO, Stirling, NJ has tons of parts. Seems a couple decades back they were selling the whole rifles. Cheap. Sometimes the service is lame. You just have to work it out. After that, if you can find a hard copy of Shotgun News (or Gun List) there are advertisers that specialize in mil. surplus parts... Tom Forest? Springfield Sporters is out of business. Then there are the importers. Century Arms, St. Albans, VT. SAMCO Global Arms. I will link thru .303british.com to sources in Canada. Quite a find and dependable quality. Best of luck with your enjoyment.