[El Gato]

With safety still on and gun pointing about 50 degrees to the cabin floor, inserted a fresh round, released the bolt and BOOM...indoors

Bet that was LOUD.

Could you tell from the wreckage what the problem was?

Sounds at first like a hammer (spring?) or firing pin problem. I guess if the pin was "sticky" and after all the cleaning stuck "out" rather than just being stiff or sticky, then you'd get the boom when you dropped the bolt.

I guess sausage must be on the menu at your place? Maybe BBQ?

[Deaf Smith]

I have no idea of the reason for the failure.

Note that just prior I had used a primed, empty case with different results (favorable).

The pigs were left for the yotes. I was by myself; packed up and drove home.