Easy sniper, assault rifle, and pistol achievements hint
On the training level after the back to back lesson, you will be told to run around the corner. There one of you will bleed out. Instead of having your partner heal you, sit there and shoot all the guards. You will not die and their bullets will be ineffective. A total of about 80 enemies will appear. When they stop, restart from the checkpoint and repeat the process until the achievements are unlocked. Note: When your health meter reaches 0 when bleeding out, your character will fall back then get back up.