Hard achievement question (The Witcher 3: Wild Hunt)

People, who read a lot of everything, how to get this achievement, they say that you need to kill 50 human opponents with a headshot, namely a CRITICAL one, but when I started to realize this achievement, I saw that different crits fly out. When I headshot, the crit is 100%, but WHITE, and sometimes (very rarely) RED one-shot! What kind of duck is needed to count hits? Many thanks for the answer! I also want to add that I changed the difficulty, but filled 50 bodies from 0!