my larger corn often doesnt constrict when it eats (its eating fuzzys to almost jumpys) It has taken several larger pinkies backwards, one of my babies took a pinky backwards today, i think 3 or 4 of our 12 baby black rat snakes ate backwards, and only a few of those constricted. I would say that as you start feeding mice that are big enough to put up a little bit of a struggle it will start constricting more often. Also, ive seen several different snakes at school constrict by just pushing them selfs against the wall of the cage with the mouse/rat pinned in the middle, and not actually coil around it.