Habroxia 2

I got this achievement on the first level by shooting one of the "turrets" mounted on the bottom of the screen. There's a section early in the level where a burst turret is on the bottom of the screen, on a bit of an escalated piece of ground. I destroyed this turret and the achievement popped immediately.

I can't confirm if it's always this enemy or if it's RNG which enemy gets the bounty.
The first level only has 1 bounty.