From reading this, it seems that the snake needs to eat more often rather than being fed only once a month. The ideal feeding schedule for an adult at that age would probably be good on a 10-14 day schedule. Start out with the 14 day schedule, feeding him a small or medium rat (whichever is about the same size as the middle part of his body). If you feel that he still seems hungry and is striking still, try to feed more often, like every 10-12 days.