Would like to see the rest of the lock plate,...looks like it might be similar to a Lancaster action with the flat spring.
The main spring is a long tapered piece of steel that runs throgh the action bar, when the gun is closed the two pins are pushed down by the bbls and put tension on the spring cocking the gun....I've only seen inside one such gun, was quite interesting, like this one

http://doublegunshop.com/roberts/fr_216close.jpg


CJ

The taste of poor quality lingers long after the cheap price is forgotten.........