If you are open the label file with Adobe and not the browser's built in reader, you should have no problem scaling to whatever value you want. However, going below 80% the barcode scans may be problematic unless you print in high resolution, and/or graphic mode, on bright white paper stock that maintains crisp black edges of the bar lines.
Plus some printers, especially label printers, can distort the bars when scaled too small. This also can occur when sending even a high resolution image to a printer that then down converts the barcode image to print it. So check under magnification to be sure.
