GENERAL SPECIFICATIONS (20X102MM HEI) This ammunition can be fired by Vulcan guns mounted on helicopter. The rimless bottlenecked case is of steel and electrically primed. GENERAL SPECIFICATIONS (20X128MM TP-T) This ammunition is produced for training purposes and is fired by 20mm anti-aircraft cannons. The shell body is same as HEIT type with front section empty and rear section filled with tracer.