I'm with Buckeye... you may have just slipped it in behind the leg low, maybe even to the point it slid along the chest wall and never entered the cavity. It could have come right out low in front of the leg. If you catch that leg and cut some muscle or even possibably break it she'll bleed for a while but will clot up and probably be fine. All she had to do was turn just the smallest amount at the sound of the shot or for you to hit just a bit to far forward.