G'day Steve,
from the proof marks, it passed proof in Sept. 1924. It has cocking indicators, set trigger with the rifle selector behind the top lever which also raises the rear sight. Saftey is the Greener type. Other than 1 other I found on the web, this is the only other drilling that I've seen made on the Echoldts patent, which makes the gun a self opener. With Echoldts system, the rear barrel lump, when closing the gun, pushes down a lever which causes the other end to load up the main springs [ if you look at the pic of the bottom of the action, the hatched area of the rear lump is really the lever and the small rectangle in front of this being the actual rear lump]. Even after firing, the spings put enough tension on the lever to help with the opening of the barrels. This of cause makes the gun a bit harder to close, but it doesn't take too long to get the knack. I make pills for this from 200gr Hornady .358 dia. projectiles [ finished size 363 dia. ] which I bump up in a swage I made. Costs a HEAP less than RWS stuff.
Regards,
Ron.