You are correct on the registered receiver. Thanks for clearing up what I quickly glossed over.
The CATCO semi auto kit uses a mix of parts from demilled STEN's as well as some of their own design to make a semi-auto, closed bolt rifle. BATF approved.
"Those who live by the sword are probably pretty f***ing good at it."
"Instructions for a successful gunfight: Front Sight, Press Trigger, repeat
as necessary." - B. Braxton