Go to survival in the campaign menu and change it to the easiest difficulty, you will need to fight 12 rounds all up, 3 in site A, 3 in site B, 3 in site C, 3 in site 4. You don't need to save all sites throughout your match as me and my friend lost a site to the enemy but still unlocked the achievement.
As there was 2 of us we went crazy with the ammo as after each round the site respawns new supply kits, launchers, bandages etc. As the round progresses it gets more difficult with the amount of enemies deployed and vehicles entering the area. This may of taken me and another player around 30 minutes to complete.
We also created a class with rifles with iron sights to help us get major progress towards:
1: Scoping mechanism
2: Eyes on the prize
Happy hunting fellow hunters