Faster Alpha Drone Kill
With the scar gun, shoot 4 things in the alpha drone then detonate them he will go down then go up to him in any direction and press y (you don't need your ulaks out).
If you are looking to kill the alpha drone or otherwise known as the big robot thing, here's what you need to know. You will need to take out your SCAR gun and try and get behind the drone. He will try and turn to face you so just keep turning with him. You need to try and stay behind him. Now unload like thirty rounds into him and blow them all off at once. Keep doing this until he falls to one knee. Once this happens take out your ulaks and walk behind him and when it gives you the option to press y and kill him do so, sit back, and enjoy the killing fun.