[DonVoigt]

That is nothing new, many of the used bolts for sale have the retaining area for the striker retaining tab worn or even worn through.

The "tab" is only about 1.5 x 1.5 mm, and is a wear point- good place to remember to oil.
Yours does look like the rear "ledge" cracked off and caused the problem, which is a little different.

When the retainer works through, it then jams at an angle and breaks- as you see yours.

The worn through slot can be welded and re-shaped, or a pin inserted to act as a retainer.
Placing the pin takes very careful work and then re-fitting of the retainer.

I believe yours could be "saved" the same way, but a new/used breech block would likely be cheaper!