Adjusting dimensions of -writer business cards

I am using LibreOffice Writer on an Ubuntu 14.04 machine and am trying to create and print business cards.

I have the stock as Avery 08371 - sheets with fine perforation for 10 cards in 2 columns per sheet.

I get the set-up and the formatting all done. All dimensions of the cards, width, height, margins, etc. Once I get the reference done to "Avery 08371, all numbers get pre-filled, and they are correct, as I can measure on the stock.

But the printing does not follow those numbers… On the printed paper, all heights are reduced from 5.08 cm to about 4.7 cm. Over the 5 rows, this means that the last row is printed over 2 cm to far up on the paper! Needless to say, this screws up everything, because the cards no longer fit the perforations!

I tried to go in at INCREASE the sizes, in order to compensate for this, but the program won’t let me.

I further tried to move the individual business cards on the page, but I can only move them in jumps of at least 0.6 cm - and that does not fit the perforation either…

The program simply does not follow its own measures, and it will not allow adjustments.

I am using a Canon Pixma MP280 printer, but that printer does not distort any other LibreOffice-Writer documents - the problem is exclusively related to printing of business cards.

What can I do to solve this problem?

Thanks for any help.