You may have to try increasing the size gradually until they fit.
If you printed one at 100%, try printing at 105% and see if that works. Print in grayscale to save on your color till you have the size dialed in.
Also, depending on which helmet you're working on, you may have to slightly alter the size of each individual template. (Just because you make "Template A" 104% doesn't necessarily mean all templates will work at 104%. . . know what I mean?)