People who now try to defend GK simple didn´t read the spoiler or see the panel because:
Law teleports right next to Kaidou. He says he's never seen a dragon's internal organs before but the heart must be around where he is now. Then he pierces Kaidou with “Gamma Knife”. Kaidou screams but he wasn't hurt too badly.
Law in fact hit his organs, most like even his heart judging his scar is right on the side.
With means Law Gammaknife hit the heart but it doesn´t work because Kaido skin was to tough with Kaido himself proof out after he tank the attack easily:
Kaidou mentions how these brats aren't just "tough idiots", they studied how tough his skin is as well.
"Law didn´t hit his organs or heart" is a nonsense claim since both Law and Kaido debunk that shit.
GK wasn´t effective as people believe, it isn´t a top tier lvl, guys with strong durability can tank that shit.
As compare Shanks can tank most like a quake attaack,but a high tier not.
Top tiers aren´t have normal skin, their durability are a whole different lvl.
It was clear that GK who almost kill Doffy can´t kill top tiers who could protect himself with haki or having a strong durability, in fact Kaido didn´t even real feel it, but Killer and the Scabbards did put more damage as Law gammaknife.
With means Gammaknife can´t ignore durability, the chapter literally proof this point.
In compare Killer attack and the Scabbard attack in Ap>>GK, for people who underestimate Killer and the Scabbards, don´t even want to speak about Zoro who mid tier Ap is >>>>>>>>GK...