I am quite at a loss: Hermann Historica never had an auction n. '263', and the mechanism you scanned is not included either in their sales no. 62 or 63.
Apart from that it is a completely average matchlock of the 1640's (!), the wingnut (Klemm
schraube) missing from the serpentine, but without any additional safety wingnut to the sear.
Please see my thread A Matchlock Chronology, ca. 1520-1720
for a very similar mechanism of ca. 1640, the ends of the lockplate also triangular: