My view is that most if not all leadscrews are soft "Not Hardened" the profile of the leadscrew is not made to be used in the scenario you describe.

So in the standard situation the most expensive part "The Leadscrew" runs in a bronze bush/nut "The Cheap Part" so the bronze bush is replaced at minimal cost preserving the integrity of the leadscrew.

The situation you describe is a bearing is used to run down the thread. Now for the problem, the bearing "The Cheap Part" is hardened and it is gonna wear the expensive leadscrew in no time at all as its harder than the leadscrew.

Now you could use a ballscrew which is hardened but then its not much more trouble to use a ballnut and get an even better solution.

Good English BTW
Phil