Caramba Fernando, ahora te entiendo
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Now i get it
I realized the set(screw) was in a lower position, in order to lock the flint screw
thread, with the purpose to prevent it to get loose and allow the flint to fall off.
Now i see that the (set)screw is in a higher position and penetrates into the flint screw 'neck', in a way that the this may rotate but doesn't fall off the jaw. I guess the reason why this is a (set)screw and not a fix pin is that, in this case, you may loosen the (set) screw and dismount the flint screw for maintainance or replacement, when its thread is worn.
I hope this is understandable ... both post text and attached drawing
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