another way of tackling this could be by setting time aside each evening, say half an hour when it is ok/safe for angry one to come out and thump hxxl out of a pillow or throw stones in the river .... or whatever you set as ok ways of expressing his anger. make sure he understands the boundries and that his 'special' time will not happen if he does not stick to your ground rules. it could be and probably is something he needs to work through and calming him down with no set time to release the anger is like caging a wild animal.. it is wilder when eventually released! you may find it is hard at first but as he releases it the sessions will get easier and eventually even may not be needed.