CSB Weapon Stats keeps a per-weapon breakdown for every player: kills (from DeathMsg), headshots and damage (from Ham_TakeDamage mapped through the attacker's current weapon). Data is persisted per SteamID in nVault. /wstats opens a MOTD table with your numbers, your favourite weapon and the most-used weapon on the server this map.
hamsandwich and nvault modules.plugins.ini, change map.