Printing without border

Hi

I have created a PDF in Adobe Reader. It's an A4 sheet but with with A6 templates displayed (2 along the top and 2 along the bottom). I have added cutting lines but exactly measuring where half way is along the top and side. When I go to print I have selected to print it borderless. However, when it prints out I am still finding that the cutting marks on the page are not coming out on the page at the exact half way marks along the top. The cutting marks along the side are okay though. I would appreciate if you could help, as I want to ensure once these are cutting up they are all A6 size and this doesn't seem to be working for all of them at the mo. Any help you could provide would be appreciated.