The frame and cylinder seem OK and not part of the cause.

That leaves ammo and barrel.

How are these barrels attached to the frame?
Are they 2 piece barrels?
Was there a gap that allowed gas pressure in forcing cone area of the frame on the left side.

I see what appears to be a Remington ammo box on the bench so should we assume factory ammo?

Without personal examination a logical explanation is an assembly defect fitting the barrel to the frame.

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