IMHO
I believe that we have been looking at this from the wrong direction. The extractor is retainer in the breech block by a pivot pin and two small flanges on each side of the breech block slot. When fired the recoil drives the cartridge case into the ejector. The ejector rotates the cartridge around the end of the breech block face pushing against the extractor. The extractor is then driven into the small internal flanges in the breech block slot.
After looking closely at the functional aspects of the breech block mechanism, I believe that there are at least two possible causes for this spalling problem
Possible insufficient clearance between breech block slot internal flanges and the extractor. Improperly fitting of the extractor, breech block and the ejector.
If the cartridge case rim is too thick upon ejection the extractor is forced into the breech block slot internal flanges. Possibly the breech block internal flanges are not thick enough for this type of forced loading.
Whatever the cause, the breech block needs to be replaced for safe use of this pistol
That's my 2 cents.
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