Series.PictureUnit2 (Word)

Returns or sets the unit for each picture on the chart if the PictureType property is set to xlStackScale; otherwise, this property is ignored.

With ActiveDocument.InlineShapes(1) 
 If .HasChart Then 
 With .Chart.SeriesCollection(1) 
 .PictureType = xlScale 
 .PictureUnit2 = 5 
 End With 
 End If 
End With