Well, I am not so sure if this is JUST a casting issue. Castings can be quite strong.

This could also be a design issue in that when an Atlas is loaded with counterweights and before the scope it put on , the Counterweight shaft acts as a lever focusing all of weight through the fulcrum of the altitude bearing and the lug that the altitude adjustment screw bears on, and transfers ALL of that pressure to a point that is less than one half square inches in diameter.

Any flaw in the casting is going to show up, but even without flaws, there is a LOT of pressure on this one spot.

As much as people overload these mounts, I am surprised that we have not (YET) seen more of this kind of failure.

A casting might not have been the best choice here so that would make it a design issue.

It is true though that any flaw in the casting would make failure far more likely.

Regards.