Hello,
at first try to change the pdf-printer to landscape. You can do this with the "select printer" function.
And if this doesn´t help, try to adjust the width of your collums.
I hope i could help you.
The next I would Try is to change the Format to A3 in your printer.
I think the Printborder is set by the size of the Page.
but can you show me your report if you print it in landscape?