If you are using starch, especially if you are using steam to press, it might be what's causing the shrinkage. I was hooked on steam until as long armer, I started to use the method of heavy starch and steam on wavy borders to shrink the excess--it works! So figured that it would be wise to quit steaming my blocks. Only time I use steam is on yardage now. I do think the Accuquilt dies (which I love) assume you are using a very accurate scant 1/4" seam!