Here is the full list of all 42 Bullshot achievements.
Find the collectables in the oil fields.
Finish the Oil Fields stage.
Finish the bio technology lab stage.
Find the collectables in the bio technology lab.
Charge 100 enemies in one game.
Find the collectables in the desert
Kill 1000 cardesians
Find the collectables in the sewers
Free all B.O.A. in the prison
Finish a stage with full health
Finish the heart in the bloodiest way
Destroy the heart of the giant worm
Finish the desert stage
Find the reader in the desert
All that glitters...
Finish the biker stage
Finish the sewers stage
Finish a non-bonus stage without jumping
Destroy the van from above
Watch the credits.
Change the settings of the TV filter.
Find the reader in the sewers
Break the car in the bonus stage
Escape from the prison
Find the collectables in the prison
Find the reader in the prison
Kill 100 cardesians
Kill 10 cardesians