Here is the full list of all 23 M.E.A.T. Veterans achievements.
Kill 100 Enemy Players
Finish round in each Game Modes
Die 20 times in one round
Progress to Level 8
Your first purchase!
Your weapon is your enemy
Headshot an enemy using a Dynamite
Burn 66 enemies!
Kill 500 Enemies with any Scope Weapon
Kill 666 enemies using a Minigun
Headshot 100 times using Revolver or Duals
Progress to Level 10
Purchase Twice from the shop
Kill 100 Enemies using Tomahawk
Kill 100 Enemies with a Dynamite
Get a 10-kills KillStreak!
Progress to Level 15
Purchase Trice in the shop!
Headshot 1000 Times!
Kill 1500 Enemies in total
Unlock all Achievements!
Progress to Level 20!
Purchase 4 items in the shop