Since the High Grade Heavyarms is the same(ish) price as the Sandrock - and that they are both from the same series - I assumed they would have similar part counts. That does not seem to be the case.
Here are the runners for Sandrock:
And here are the ones for Heavyarms:
Granted, the runners are different shapes, but it still feels like Heavyarms has more going on. For example, its “A” Runner (the one in the center) is the full size of the box.