Nice find Axel and one nevers knows considering that some early guns were made to fire both pinfire & central-fire, who knows some craftsman may have developed a means to fire bother Flobert & central-fire?
Such an interchangeability is impossible. Apart from the need for two firing pins, one for the center, the other hittng the rim, the chamber precludes interchangeability: The 9.1x40R had a base diameter of .401", so the .379" base of the .38 Sp family is a loose fit, but the bulged out fireformed cases work at bp pressures. The thin-walled 9mm Flobert rimfire case has a base of only .346"! This would be grossly undersized in a 9.1x40R chamber, resulting not only in split cases, but also in very questionable ignition. It would be about as likely as a rifle with two firing pins to use the .22 Hornet and the .22 Magnum rimfire interchangeably.
