I am perfectly confident that the OP is quite aware of his failure to follow the basic rules of gun safety, and his defensiveness is merely from his resentment at having found himself in a situation where he reacted poorly. His resentment at the situation also did leave a poor first impression of his attitude, but I'm not one to judge others on that alone.
RX-178 - I do not know where/how you get the impression that the OP is "quite aware of his failure".
Not in any one of his responses subsequent to his first post, has he indicated that he might have reacted incorrectly and that he needs to re-assess the recurring situation and his own responses to it.
He blames the house, the alarm, his mother, the economy . . (I am surprised he is not blaming Bush).
NOT ONCE does he take ownership.
Not once does he acknowledge that he might be reacting incorrectly to his mother's actions.
Not once does he acknowledge that maybe he needs to sit down with both his parents and discuss the situation and finding a solution that will work for everybody that shares the house.
It is his parents' house. Due to economic necessity, he is forced to live with his parents and accept their hospitality.
He has to understand that he is not in control. It is not HIS property. If his mother wants to come and go as she pleases and in the process accidentally sets off the alarm, he needs to learn how to deal with it.
If my son pointed a gun at my wife's head in my house . . . . . he would be out of MY house in no time flat. (I was going to be more graphic, but decided to be High road)
He is there at his parents generosity and he needs to deal with it. NOT come here and call his mother a BONEHEAD for his boneheaded action in HER house.
I am sorry, the OP is the bonehead in this situation and he needs to apologise to his parents for putting his mother's life in danger.