Thanks for the fast reply TWA.
I know what you mean about single point, I'm not sure it the solution for a heavy rifle like a FAL...however this adaptor can also be used with a standard sling too.
I think I have the profile for it worked out (from measuring a stock) I was just unsure on the material. 1/8" seems reasonable. Now to decide on the material, I can use Stainless 316, chrome moly 4130. Both are cheaper than hot rolled steel oddly.(this is via an online service).