I am using a macro to extract mass properties data to Excel, and I'm using the GetMassProperties method (from IModelDocExtension) to get this data from the parts. The only issue, though, is that the mass that it seems to get for the parts that do not have assigned mass appears to be a little off from what SolidWorks is reporting for that part in the mass properties issue. Is there a reason for this? Is this just inherent to the GetMassProperties call?

     For example, in SolidWorks, when I click on mass properties for a certain part I get 2.393 kg. And when I run the macro, the mass for that part is getting returned as 2.418 kg.