What a BB ... wall thickness way higher in places than others, looks like they've used an electric sander with 50 grit sandpaper to 'smooth' it, and it doesn't look round even to the naked eye.

Naked eye is deceiving, the only way to check roundness is with a vernier calliper. It is round within 40.92 and 40.94 which was slightly undersized but not oval and certainly cannot be detected by the naked eye.
The so caller " 50 grit" is only due to the quality of the picture which distorts the reality,  BB has been machine very smoothly equivalent to using around 200-300 grits
The wall thickness is questionable indeed