take out one piece of shot and you will likely balance it
but - why are you adding the card? poor crimp?
i use these over buffered loads to keep the fine powder from leaking out which sometimes happens even with a good crimp ( i have opened flats of factory buffered shells and found some buffer powder has come out)
https://www.precisionreloading.com/c...#!l=PRP&i=TS12
they are so thin I find I often have two or even three picked out together - and they are very flexible so there should be no affect on the pattern