Is there a blank firing adapter for the 17S out there?
I have not found one through my usual internet searching...
I believe there is one issued with
the guns as part of the kit, but I've not seen any commercially
Yes their is a BFA for the 17. However it attaches to the SCAR's flash hider ( which in most military applications is a AAC 18T Miter Mount) and not readily available to the general public.
The BFA for the 17 and the 16 are both different in the way they attach to the flash hider as well as being caliber specific.