What is now known genericaly as a'Southgate'type ejector refers to a system of 'over-centre' principle forend-housed ejectors that are refinements of patents by Southgate, Beesley and Perkes.

They differ from other basic types, liek the Deeley (a forend housed lock), the Boss (coil spring) and the Greener (self-acting and powered by the mainspring).

All the patents can be found in Crudgington & Baker vol 2.