An aft closure assembly manufactured from two separate and distinct pieces made from different materials is provided for a rocket motor case. The aft closure assembly includes at least a retaining ring piece made from a first material similar to or having a coefficient of thermal expansion similar to that of the motor case. The aft closure assembly includes a blast tube and closure piece that can be manufactured from a second material that does not need to be similar to nor have a coefficient of thermal expansion similar to the motor case and retaining ring piece. This is possible because the blast tube and closure piece includes a face seal that seals against a face of the retaining ring.