The screw going up from the bottom of the wrist and threading in the tang was standard practice on even the highest grade guns made in France, and those areas of influence, from pretty much the inception of the flintlock until the Thruain and Le Hollandois style ended around 1660. It hung on in some regions such as Liege and regions of Italy, well into the 18th century. It's also of note that this is one of many examples where trade gun technology and style was heavily influenced from deluxe guns of the period. Typically there was a lag time before these details appeared on lesser quality guns and they often hung on for a considerable time after they became out of fashion for higher grade guns. An example is the serpentine sideplate. It first showed up in Paris in the late 1650's and lasted until around 1700 or a touch before, but was used on trade guns until the late 19th century!
