Here is the full list of all 12 Trigger Happy Shooting achievements.
Got 60 points in Target Training
Got 55 points in Bottle Range
Got 45 points in Hostage Training
Got 70 points in Gold Challenge
Got 50 points in Red & Blue
Got 50 points in Range Training
Got 50 points in Vase Breaker
Got 65 points in Horse Run
Got 22 points in Sniper Training
Got 33 points in bird hunt
Unlocked all weapons
all achievements complete