I'm not a fan of spray and pray. The effective range is too short, and there are too many variables to ensure a reasonable expectation of a desirable outcome. The key to success is preventing the bear from making physical contact with you; he can't hurt you, if he can't touch you. There are all sorts of environmental elements that can interfere with the stream of bear spray from landing effectively on the target, but worse is the risk of incapacitation of the individual who is still in a dangerous bear situation. Heavy vegetation and wind are both considerations in regard to back splatter, and if a bear comes into your tent, do you really want to unloose that can of bear spray?
Firearm failures on the other hand are directly related to the mindset and prowess of the shooter. Clearly there are some people who are incapable of protecting themselves with a firearm, but that shouldn't have any bearing on those of us who can. Defensive shooting requires a different skill set than hunting does. In hunting we are mostly conditioned to making a chest shot. The hunter is concerned with a shot that produces a quick humane death, and the chest provides a large target that can be hit from almost any angle. Typically though, it takes several minutes for a large animal to suffocate or bleed out from a chest wound, as its oxygen deprivation that ultimately kills the brain.
In defensive shooting that won't do. Defensive shooting requires the shot to instantly stop the bear's forward progression; which isn't necessarily a kill shot. A CNS shot will stop the action in a suitable fashion, but in another circumstance, if the bear is focused on a companion, it might be safer to hit a large supporting bone, which is farther away from your companion, and gives you time to reposition to safely make a kill shot. The bear that comes directly towards you provides the easiest marksmanship problem to solve. The bear's length coincides with the path of the bullet, so its not difficult to hit the centerline of the head or the spine, even when shooting quickly. Just shooting the bear in the head isn't the answer though. When viewed from the front, the brain is only the width of the snout, and it lies behind the eyes to the front and ahead of the ears to the rear. When the massive head of a bear appears in front of you at close range, it is very distracting, but the center is always the center. A shot that hits a bit high still cuts the spine. If the bear's head is swinging back and forth, the "stationary" spine is a safer bet. The point is that filling your sights with hair and pulling the trigger likely won't improve the situation. The bear might approach you from above or below, or quartering towards you, all of which present complications, so think of the target in 3 dimensional terms.
