Second Extinction

You can do this solo or with friends. This solution works with all the deployment related Achievements.

I recommend turning your Achievement tracker on and favoriting the Achievement so it shows on top.

Just start a free roam expedition or a campaign level, select your character and a drop point then after pressing A and spawning in the drop ship you'll make progress toward the Achievement, immediately press the Menu button, select Return to Main Menu and repeat until the Achievement pops.