expression.ColumnWidth
expression Required. An expression that returns one of the objects in the Applies To list.
Remarks
One unit of column width is equal to the width of one character in the Normal style. For proportional fonts, the width of the character 0 (zero) is used.
If all columns in the range have the same width, the ColumnWidth property returns the width. If columns in the range have different widths, this property returns Null.
Example
This example doubles the width of column A on the datasheet.
With myChart.Application.DataSheet.Columns("A")
.ColumnWidth = .ColumnWidth * 2
End With