[ithacaartist]

Whatever the heat treatment for receivers was, the repeated pounding of use will tend to work-harden the material, making it more brittle. I agree with the idea of examining the mating surfaces of the break, which might give evidence as to whether a crack had been forming, long-term. Newly-snapped parts will be clean and sparkly over the face of the broken areas, and a crack that developed in the past, and finally let go, would show darkness/dullness/discoloration/oxidation in the extent of the ancient beginnings of the break. A good lesson to check these old girls out occasionally, under magnification--if not a session with leak-check and developer (harmless to the finish).