Shot placement is important, but the more the bullet expands, the more tussue it tears and destroys. That contributes to blood loss and shock, which is what will go farther to stopping or at least slowing him down. Sure, FMJ to the central nervous system will do the same as an expanding bullet, but you have less surface area with which to hit that CNS. Failing that, I want as much tissue damage as possible. Even if it doesn't create an actual stop, it saps his will to fight.

You can practice all you want, but you have to remember that in a crisis you will not be shooting at stationary paper targets. Don't count on hitting the heart, or the head, because they will be moving, and shooting back. Give yourself every advantage you can. Better bullets are an advantage. It can be argued how much of an advantage, but if nothing else, if it expands to twice it's diameter, that's more area to hit those vitals.

I order all of my social ammo on line. Streichers, MAH supply, ammoman, all are good. Ammoman tends to have the best prices, but he doesn't always have stuff in stock. I know he has HST in .40 right now. And I think he has Gold dot's in 9.

I don't recommend SXT, but rather Ranger-T. It's a different design, and performs better. MAH Supply carries it, though a lot of it seems to be out of stock right now.