Buddhist view on letting the anger out. Any problems with that? Many people claim they feel better, like a strong relief, after letting the anger out, so they scream at the open air or punch a sand sack.

Of course I'm referring ONLY to cases where there is no other person involved, so I'm NOT talking about punching a person or yelling at someone!

I know the Buddhist view on anger is to see it for what it is and let go of it, but some people see it as suppressing the anger and keeping it in, so they claim that letting it out is a better way to get rid of it. It works for them.

So, is there anything wrong with that from a Buddhist's standpoint?
The idea is called catharsis and it basically treats anger like hot water or steam that can be released when the pressure is too much. It is true that letting anger out like that does tend to produce relief, but many psychologists are of the opinion that doing so just creates a positive reinforcement of the angry behavior and over the long term simply increase it. Here's a link to just one study on it, but you can find more just by typing anger and catharsis into google scholar:

https://www.mtholyoke.edu/courses/jbickfor/bushman2002.pdf

From a Buddhist point of view, actions which are based on strong aversion are very unwholesome and are thus bad karma and so acting out on a feeling of rage is just digging yourself deeper in the hole. 

It is much better to get rid of anger by reflecting on the dangers of anger, the value of patience, establishing one's self in mindfulness, and by trying to generate metta towards the object of anger. Is this easy to do? No, it's very hard, but that's because it is a training. Serious training of any kind always takes a lot of effort to produce results. Practicing in this way will bit by bit give us a totally different way of relating to the world around us.