Wasn't it RPB or Cobray that came up with them? I used to get these plain black and white sales brochures from Cobray back in the mid 90s. I screwed up and bought stamped out receiver flats to build a closed bolt semi M11 and the little M12 in 380. What a pain in the ass! It would have been SO much easier just to buy one of each. But their flyer things that came folded up like a road map always had cool stuff in it. There was always some kimd of 37mm laumcher and parts kits for the open bolt semi an FA guns. You just dont see that stuff anymore,He means no go as in there are regulations. There are transferable lightning links, but any newly manufactured post sample lightning links have to be done by an FFL/SOT holder and aren't transferable.