Why does ADE shrinks the content size of my PDF file when I try to print it?

My PDF file has Digital Rights Management (DRM) which restricts the number of printed copies I can generate via Adobe Digital Editions (ADE), however, the size of the printout is shrunk by some percentage depending on the printer I selected.  For example, on my HP Deskjet printer, a 5" x 7" image comes out 4-3/8" x 6-3/16", even though on the printer preferences dialog box, I selected the actual size (100%) for the printout.  It seems ADE adds margins on the side of the page which shrinks the content actual size. 

Does anyone know how I can print via ADE without the margins added on or tell me the percentage of shrinkage on the printout from the actual size of the content on the PDF?    

Any help would be greatly appreciated.