goodshot:
FWIW, a Pit Bull's head is so hard and bony, that we're trained to shoot at their body mass and not the head. Bullets frequently just bounce off their skull if shot at any kind of indirect angle, so even putting one down with a handgun can be difficult.
There are numerous web articles on this subject with some other good tips. Best Wishes.
No, you need a really high effective obtuse angle to get that kind of deflection with any decent sized round, even a 9 mm, and definitely with a .40 s&w or a .45 acp, headshots from dead on or from the side are guaranteed kills with good penetration (even barely breaching the front skull wall with result in significant fragments entering the brain), gel tests confirm this. As you know, they teach you to aim for center mass because it presents a much larger target from which to send multiple rounds at a quick rate with high hit percentage as well as affecting a greater number of critical organs, same as in the military. The thing is, this won't always put it down for good right away, in these cases, it just happens to often become mortal wounds. If you are good, in an encounter you may have time to aim and fire off 1-2 decent shots at the head, which may or may not hit given how fast dogs are and their general attack vector. Shooting at center mass will let you get off at least 3-4 rounds with higher chance of hit, and possibility of slowing it down in the process; given it's not just a flesh through and through, they will die later if they are deterred and flee, or you will have an opportunity to put more rounds in it.