Square vs round cylinder notch ??

[tx77057]

I have noticed that the evolution of the walker to the 2nd model dragoon changed the notches from small oval to larger square. Is there a funtional reason for reliability or to ease production??

[Flint]

The rectangular bolt and notch function more smoothly, and hold position better, it seems.  The rectangular bolt can be fitted better and more easily, and locks up tighter.

I'm sure it is also easier to manufacture, as it's the same width as the bolt body and doesn't need to be shaped into an oval.