Just bought an underlever 20 gauge hammer gun. Only markings on rib is..John Heibner..Gun hasn't arrived so I can't see flats stamps. I would guess German of Belgian..I have checked everything I can think of..and that name never shows .. Also..is there a source for replacement hammers ? One is different from the engraved one...Please let me know if the name rings a bell..thanks..jv..........