Thats total lead. I doubled what I'd normally lead in any other game ie: DOD. Looks totally unreal but it killed em, gotta be a hitbox/netcode issue. I play on two servers that give me pings of 15-25 so its not a lag issue.
If they are still I kneel, hold the cursor on em for 3 secs then fire and I'll kill em.. if I fire instantly they'll take the hit and not die.. very unconsistant.