The true Flobert has no firing pin and no breechblock. It fires rimfire cartridges by a ridge machined (or cast) into the face of the hammer. The user cocks the hammer, loads a cartridge into the chamber, then pulls the trigger. The hammer falls, the ridge firing the cartridge. NOTHING holds the hammer down (breech closed) except the momentum of the fairly heavy hammer. Let me say that again. NOTHING HOLDS THE BREECH CLOSED! There is no lock, no breechblock and no firing pin. Some have extractors, but others depend on that old extractor, a fingernail.
Obviously the system works ONLY if the mass of the hammer is sufficient to keep the case in the chamber against chamber pressure. If not, the case is blown out of the chamber (NOT "extracted" - it is blown out) pushing the hammer down and back and flying off someplace around the shooter's face. If the round is powerful enough, the hammer may be broken and possibly become part of the miscellaneous pieces flying around.
Most of those guns were not made of steel, which can be welded. They were made of cast iron, which won't take weld, which is why cracks were brazed.
'Nuff sed. Anyone who values his or her eyes should NOT fire any of the original Floberts with anything.