They don't worry so much about orientation until the prey is "dead".. Try giving the rat a little wiggle if the strike/coil is less than enthusiastic. Your snake should wrap all the more tighter to counter the "struggling" prey.
My father kept snakes in his classroom for more than 20 of his teaching career years. Feeding time always drew the crowds - super fascinating stuff! I've been keeping herps over 20 years now and I'll still watch my faster eaters(pituophis). My bulls take all of 30 seconds to swallow an appropriately sized meal, quite a change of pace from the ole regius.