Well Itachi's attack on the CT is a bit different then the multiple magatama shooting that he did against Kabuto near the beginning of their fight. It seems like a condensed form of it. I highly doubt Itachi could pull off enough to destroy something like CT though (obviously not counting other attacks). Kishi did showcase that the magatama's piercing effect is pretty powerful though, seeing how far they got through the Gaara+Onoki defense combination via Madara (honestly it's pretty much the same idea).