Cracks appear to have been a result of the sharp corners which were stress risers. When that gun was made the physics of stress and its causes were not well known.
It is a cool gun fore sure, wish is was in better condition. I'm not sure if I understand how it locks up. I would assume the side lever cams the barrel back into the breech section. The listing says the, "locking lock missing." Which explains why the action is both open and closed in the pictures but the lever hasn't moved.