The article only says pistol, which means it could very well be a .38, especially if one considers the hand strength of an 80 yo man. Even a .22.
One of the traits of the pit bull type dog is the “block-head” skull. So a head shot might not quite do it quickly.
The head shots missed by a little too much. In the past, I stunned large cattle and hogs (over 600 lbs.) for slaughtering and butchering with a .22LR and never a miss. Stunned a large bull for some neighbors once with a .22. They all went out like lights.
From the front, the round needs to go into a tiny area *within* a half an inch above and between the eyes and at a slightly downward angle (not far from perpendicular, not too oblique). Applies to dogs, too—same anatomical target. From the side, the round needs to hit the midpoint between the ear and the eye. Imagine a straight line between the ear and the eye while viewing the head from the side.
Find something more powerful than a .22LR for defense against a charging pit bull, though. Too hard to hit the right spot on a fast moving animal. Accuracy is important.
Making sure that the round does not hit a bystander in the background is of the greatest importance. Be very aware that the round will most likely blow through the animal, ricochet off of the ground behind the animal and hit anyone in that direction.
If a small dangerous animal is latched onto someone and stopping the mauling is absolutely worth the risk, then fire at the spine and *away* from the person being bitten. And make sure that there is no one behind the animal in the direction that you are firing.
Study ballistics. Study anatomy.
A lighter round or a bullet without great expansion could also ricochet back at you from a bone in the animal. Shooting a dangerous animal in such a situation would be risky. Remember that ricochets can possibly come right back in your direction (e.g., hitting a rock perpendicular to its surface). If you’re going to try to put down a pit bull for a good reason, doing so with the animal away from any and all people would be best.
Be careful. This is not advice to tell anyone to shoot a dangerous animal with other people in the background (including anyone in houses in the background). It’s only a little information that might be helpful to someone who’ll do it anyway.
If using double-ought buckshot with an 18-and-a-half inch, 12-gauge straight cylinder (cylinder bore), you need to pattern it first by firing at a target from various distances. Your pattern shouldn’t be any larger than the front-view profile of the animal being considered. You might not want to fire a 12-gauge with 00 buck at a pit bull from more than about 10 yards.
Oh...and if you ever stun a large animal for slaughter with a .22LR, don’t use hollow points. Use the cartridges with heaviest round nose bullets.
Not only do they have block heads, their necks are solid muscle the size of a gallon paint can. They are great at grabbing and shaking. Give them the toughest chew toy and they will destroy it with their powerful jaws.
No matter what you are going to shoot them with, their head is going to be a rapidly moving target.
If you want one, get the help of a profession trainer if you have any trouble controlling it.
Nothing wrong with a .38. Not a nominal caliber at all.