This image shows malt samples milled with a 0.65 mm (26 mil) mill gap. The left hand sample has been conditioned and the right hand sample has been milled dry. The conditioned malt’s volume is about 30% larger than the dry milled malt’s volume.
Conditioning you malt helps you to lessen the crush you use and access the fermentables. Another site recommends you can actually increase your crush.
Here are a few links to start your exploration.