Hi rob,
1) ColumnWidthToPixels property is used to convert the ColumnWidth to Pixels. It will return the columwidth in the pixel format. You can use this property to get the column width in pixels.
Here is the sample for your reference to get the columnwidth in pixels.
ColumnWidthToPixel.zip
2) But you can not set range.Cell.ColumnWidth = pixelValue. Because range["A1"].ColumnWidth will not set the width in pixels. You can use this property just to get the column width in pixels.
Please take a look and let me know if you have any other questions.
Thanks,
Melba