Here is the full list of all 10 Aim Trainer X achievements.
Hit the center for the first time
hit the center 10 times
hit the center 100 times
hit the center 500 times
hit the center 1000 times
have your reflex be under 100ms in one hit
finish a round with 100% accuracy
check your stats menu
miss every shot in a round
play sniper mode 10 times