Here is the full list of all 11 Gunbrick: Reloaded achievements.
Hit 3 people in a row with the same bullet.
Complete the game.
Squash 100 people with the Gunbrick.
Destroy 100 robots.
Squash 30 robots.
Complete 1st pack.
Complete 2nd pack.
Complete 3rd pack.
Complete all levels in 1st pack without dying.
Complete all levels in 2nd pack without dying.
Complete all levels in 3rd pack without dying.