Call of Duty: Black Ops 3 - Throwing Flak Achievement/Trophy Guide
For this achievement/trophy you'll need to kill 3+ talons with a grenade explosion. This can be done as early as Mission 2: New World but can also be done in Mission 4. As soon as you see a group of them flying, cook your grenade and throw it so it explodes as it reaches them. If you kill all of them the achievement will unlock.