Yep, check Gun Parts Corp or Midwest Gun Works is also a good source. Pretty sure they have both the individual rings and a complete factory rebuild kit:
I have found Browning to be cheaper on parts than either of the other two sources mentioned. I assume from your post, you are looking for Browning parts. Simply, go to the Browning web site.
I seem to recall one parts source used to want around $65.00 for the "tune-up kit (so to speak)" meaning various springs, rings and etc. The price for the individual parts combined from Browning was half the price. Browning does charge a fixed price of around eleven bucks for shipping. Not sure what the other suppliers charge.
I ordered a number of small parts from Browning for my old Auto 5 a couple of months ago. The order items were received promptly.
The A5 was discontinued over 10 years ago, Browning does not support over 10 years.
For parts and a factory service manual go to MGW they handle all kind of parts for Brownings. The service manual can be down loaded from their web site.
I beg to differ. Go to the Browning web site and click on "Support" at the top of the screen. Then click on "Parts and Service". You will then see a screen showing the cover picture of John Browning on the Catalog. Click on the picture and it opens the catalog. You will then want to enlarge the pages. There is an index of guns supported. The Auto-5 is on pages 1, 2, and 3. Page 1 & 2 show the part numbers along with noun nomenclature and price per part. Page 3 is the schematic on the shotgun identifying parts. The 12 gauge bronze friction ring cost $6.00. It is Browning part # B1111197 and the noun nomenclature is "Friction Piece Bronze".
You will also want to download the order form and address for ordering parts. All of this is available on the web site.
I placed my an order for various Auto 5 parts back on August 31, 2010 and received my parts about ten days later. I ordered nine different parts and received everything I ordered. My Browing Auto 5 is dated 1930, and all the parts I received fit perfectly.