The ejector mechanism in the lumps and action is another Greener clue. That would make it either a "Self-Acting" ejector or a "Unique" ejector. Judging by the reinforcing bolsters at the angle of the frame, it is probably the later, improved, "Unique" model. The Facile Princeps had ejector work in the forend. The Unique and Self-Acting models are referred to as G-guns and are complex guns that were made only by the most skilled craftsmen.