Very well observed, Manuel,
But South Italian, Sardinian and Turkish miquelets too have vertically ribbed frizzens in order to produce a bigger shower of sparks.
Fernando, there seems to be indeed a certain French influence in both the decoration of the barrel and the embossed silver on the stock. As there is no doubt that the lock originally belongs because the figured stock closely follows its characteristical contours, especially at the bottom line, the thesis of a French export model in the Portuguese or Spanish taste is worth considering in my opinion.
Best,
Michael