Barcode 128 formats and Code 39 Size Changing

Hello Support,


   We have noticed that the barcode bar width in the BY tags multiplier is changing from time to time.  For instance a barcode value of just the letter a in say code 128 for a BY value of say 4 is not staying the same size in width. Is there some setting or tag that can be sent to a Zebra printer that will change the width of the bars in the BY magnification?  Can this program happen do to a particular calibration.  This matters because people have to certify barcode widths for label standards and if they change it cause real problems like charge backs etc.  












Nathaniel Nesler