This all looks rather similar to the system employed by Osterr. Waffenfabr. Ges. Steyr for their pre - WW2 Mannlicher Schoenauer Take Down Model and also by Westley Richards early in the twentieth century:

Mannlicher Schoenauer

Here is the 'rear tang' where the action lugs in. This is the optional 'special folding peep sight' offered on the MS (and on Mausers) sold by Stoeger.

The Mannlicher Schoenauer Take Down System;
Notice notch at rear of magazine well that engages catch when lever is turned fore of the trigger guard (lever and trigger guard remain with stock when disassembled). Three points of attatchment are; 1) pin through barrel band and forend escutcheon of stock; 2) machined slot in tang to machined receptacle which remains on stock, 3) cam / lever fore of trigger guard which engages machined slot on outer rear wall of magazine well. The magazine cover plate, when closed, also locks action to stock.:

Lever

Another view

My Mannlicher Schoenauer M1910 (with fitted case) is a Take Down Model and the system works flawlessly as described in the catalog image above. Remove magazine, turn lever fore of trigger guard, pull forend pin, out she comes and nestles back in place with precision when reassembled.

Grand - Dad with M1910 Take Down Model in the field (Ceylon), 1932.

here's an MS from Dorleac: Dorleac