The fact that he gets angry when you talk to him tells me he knows he needs the alcohol, and he doesn't want you to come between him and his drinking. I agree his intake and history is problematical.
At 20 he might progress to alcoholism, or he might decide on his own to moderate or stop. My own son binge drank in his early 20s, but calmed down with maturity. I still watch him though; can't help it.
There is nothing you can do to force him to stop. When they get to that age, especially boys, you have to take a step back, zip your mouth and cross your fingers because they will feel a need to defy you. You can actually become counterproductive, and you will drive him underground (all the above assumes he's not driving drunk or putting himself into danger).
When he moves away he will have his own freedom to make drinking decisions without feeling he's giving in. I hope he comes to the right conclusions, based on a good upbringing and family sense of values.