I've had them go down like that with several hits other than spine shots. Heart/lung would be on the top of the list. The other was a shot under the spine that cut the major artery leading to the kidneys.....down in 5 yards. The third was a jugular hit on a caribou which went about 5 yards and another on a small buck last season that went about 10-15 yards. In regards to heart shots, it has been my experience that hitting the heart directly puts them down quickly but not as quick as a shot that severs a major artery leading directly from the heart. Femoral artery is similar but the one deer I killed with that shot made it about 35-40 yards and there was blood everywhere but I did not get a pass thru. In addition, some deer get fatal shots and don't even know they have been shot and continue to feed...so the distance the deer travels and the amount of blood on the arrow can be misleading and not correlated directly. The moose I killed two years ago only went 3 steps with no more than 12inches of penetration....low in heart,low in both lungs, hit off side leg and the arrow came back out on the first lunge.