James, I would check on large gun and accessory sites like (6)un (8)roker, Armslist etc as discontinued and hard to find firearms and accessories show up for sale by private individuals and small shops. Just replace (6) & (8) with G & B.

I would check a big website with the second part of the name called Broker. Also one that starts with Arms and list. You might also want to check online forums, especially Howa specific ones. The Axiom was a joy when I had one. I traded it for an old little pistol. It was my pleasure to assist you.