Here is the full list of all 11 Sniper Tactical achievements.
Kill 1000 enemies
Not only leaves are gonna fall in this forest.
If you see the flash....
You are always covered.
Heavy sandstorms are the nice variant for bad guys.
Kill 1000 enemies with headshots
Kill 100 enemies
Roofs are now a safer place to hang out!
Art of sniping mastered!
Kill 9999 enemies
Kill 9999 enemies with headshots