I was thinking it might be similar to the Sauer - Belgian connection but it was shaped like a Boxlock:

J.P. Sauer Triggerplate Round Action:

>>Though this ultra-rare Sauer & Sohn gun is not recorded anywhere, asking around showed that tales about it are still known among old Suhl gunsmithes, one of them even remembering having such a thing repaired and restocked many years ago. It is remembered as a major blunder of the major gunmaker Sauer&Sohn.
As both guns show pre-1912 Suhl proofmarks, dates from 1906-10 may be ok.
In the early 1900s the Anson& Deeley boxlock action was not so entrenched as it was post-WW1. At that time Sauer & Sohn, always on the outlook for new designs that are easier/cheaper to make, were offerd a "novel" design from Liege, the Belgian Gunmaking centre. Just to give it a try they bought in a handful of these actions in the rough from Liege and completed them. The resulting guns were not to their liking, so they dropped the design after offering the few guns, apparently for export also.Less than ten were ever made. The design proved to be as complicated to make as their then standard designs, so there was no advantage here. The stocks had to be hollowed out a lot and were prone to breaking, as there was little wood to metal contact.. The handling qualities, weight distribution, were unsatisfactory.
As usual with most break-open guns, the action is a recombination of known design features. So this action was probably never patented.
The design with triggerplate locks, but mainsprings inside the action bar, is a relative of Tranter's gun, British patent # 1881 of 1882, sold by Tranter's son-in-law Watson as the "Carlton gun". Some Belgian substituted Tranter's cocking lever with a slide, pushed back by the inclined rear surface of the front lump. In the photo of the watertable above the roller on the slide that bears against the front lump is visible.
Nevertheless, I am still interested in how the cocking of the locks is accomplished. In the photo of the watertable you can see a roller in the forward cutout for the front barrel lump. Apparently this roller is forced back by the incline on the lump to cock the locks. This roller may be attached to a seperate cocking slide, but a simpler solution would be the mode of the British Gibbs & Pitt "Second Model". Here the locking underbolt forces back the hammers. On the First model G&P, British patent # 284 of 1873, cocking was accomplished by turning the toplever 90 degrees, which pulled back the underbolt far enough to cock the hammers. On the second model, dateable before 1887, cocking is just started by moving the toplever until the barrels are unlocked. Then an incline on the front barrel lump, very similar to the one on this "Sauer" gun, takes over and pushes the underbolt back further until the locks are at full cock.<<

https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=261189&page=all

Serbus,


Raimey
rse