Series.PictureType (Word)

Returns or sets a value that specifies how pictures are displayed on a column or bar picture chart. Possible return values are xlStack - The picture is sized to repeat a maximum of 15 times in the longest stacked bar, xlStackScale - The picture is sized to a specified number of units and repeated the length of the bar, xlStretch - The picture is stretched the full length of the stacked bar.

With ActiveDocument.InlineShapes(1) 
 If .HasChart Then 
 .Chart.SeriesCollection(1).PictureType = xlStretch 
 End If 
End With