it is a good set up. i think it was MGI that was making those.
one of these days i may pick one up and hang it over on the AK side of m lock down racks!
it does require a special machined carrier that make it sort of an odd duck--but i figure an gunco member could machine that himself with no sweat.
i don't think the AK mag ar is made anymore. the last one i saw was used for $800 over at guns america. i think when they were sold new the were way more than $800 which is probably why the never really caught on.