How does the 'High Caliber' award work?

Solution 1:

Taken directly from the WoT Achievements guide:

https://worldoftanks.com/en/content/guide/general/achievements/

High caliber:

Awarded to players who dealt the biggest amount of damage during the battle. The damage dealt should be not less than 20% of enemy team tanks' HP sum, and not less than 1000 points. For receiving this award, allies should not be hit with direct shots. If two or more players have an equal amount of damage dealt, the achievement is granted to the player who has earned more XP for battle, including additional XP provided to Premium account users. If the amount of XP is equal as well, the achievement is not granted.