ok from your piccy..im a bit lost,, so,,
is it just a rail mounting ASA your after,,,
or is it a rail on the bottom of your grip your after,,
as you can see from the photo,, that rail is built in to the grip,,so you cant buy it on its own,,
i can machine rails into grip frames,, or you can just buy a bolt on rail,, i do make some thing like this,,
hope this helps,,