Winchester scope Problem

I just bought the winchester scope and though this gun may be a high damage gun, so i go use it. So I use it in the match and notice far range hit to the head (and I was aimming for an afk guy standing in a middle of the map) noticing everytime I do a headshot, ig got like 9-10 damage, on the head? so then I go rush and close range it do headshot fine but far is like a bs pistol with no damage, it is me or that stupid winchester scope is a close range rifle?