There should be about 0.05 mm play. The vendor has to match the balls to tune the free play / ease of rotation depending on the fit of that nut on that ballscrew.

Nominal ball size (for 1605 1610) is 1/8” of an inch (3.175mm) but they can be tuned up or down in something like 0.02 mm steps. Some vendors will then engrave this number on the ballnut(Fred at BST for example). So they may be marked +2 for 0.02mm oversized.

If anyone has links to these tuning sets I would be interested as one of my spare ones could be dialled in better. Seem to remember Lee had some ??