Just to add a bit to what has already been shared...
And NOT having the lock and gun in my hand...
The Italians are notorious for random hardness, tempering, and other metal treatments. And sometimes, who ever cut the half cock notch position ha sit in the wrong place so rather than balance between sear spring and mainspring sliding it past, it falls into the incorrectly located notch. Or sometimes the shape of the sear nose, and the shape of the half cock (or full cock on another problem) is too far "off' to allow the notch to function properly.
Not saying it is, just throwing out some other Italian "maladies."
In gleichem Schritt und Tritt, Curt Schmidt
Not a real Civil War reenactor, I only portray one on boards and fora.
I do not portray a Civil War soldier, I merely interpret one.