Originally Posted by
Europa01
Yup - I’ll concede they do look flat in that photo.
Very likely that they are flat. In combination with the compensating nature of the swivel type contact shoe it provides the highest chance to have a flat clean contact.
If you go sherical one would need to match 24 centers to prevent point contact. Form deviations of the sherical faces come on top of it.
Mission impossible already with 2 perfectlly spherical pins slightly out of position.
Make a sketch and you will see it will only work for 1 pin.