http://www.ballisticsbytheinch.com/9mmluger.html
Jim Downey's website is a God send, since he actually tests current ammunition in real guns, AND test barrels.
The test barrel data gives you excellent data on how well the ammunition works in your barrel length. From this, you can figure out the speed of the powder used in the different ammunition.
General loading practices that lead to accuracy.
A full case of powder. This means consistent ignition, and burning, since the powder can't settle to the side of the case, or move away from the primer when it's slammed into battery out of the magazine.
A powder designed to work in your gun barrel length. If you use a slow powder, you end up with a lot of powder burning outside the gun, after the barrel, after the bullets departed, unless the bullet weighs 350 grains or more, then the rules change.
Finally, with 9mm, it's easier to have consistent loading practices with larger bullets. The little ones are hard to seat properly, and, are difficult to work with. Longer bullets also tend to correct errors that might affect a smaller bullet as it goes down the barrel. They are also a bit more likely to provide more resistance, therefore helping provide resistance, and, a more complete powder burn.
All that said, there are more ways to skin a cat then one. Light fast, mainly .357, with 125 grain bullets, at 1450 fps, or more, has a long proven track record of working. If you can get your 9mm to do this, go for it. That will depend on barrel length.
250 grains at 950 fps has also worked. Many different formulas, and, a couple different wounding types that both work.
Gerard, that's the owner of GS, is on to something. The speed at which the bullet impacts can determine expansion. Skin is actually pretty tough, and, when struck at high velocity, it can cause bullets, depending on design, to expand violently, and parachute in a shallow channel, shatter, or fragment.
It can, as his HV's do, all so be used to create a multi-fragmented bullet, that has tremendous impact, since the impact sheers off the 4 petals of the bullet, leaving behind those 4 projectiles to do damage, along with the core, which penetrates like a flat nosed wad cutter, straight and true, and, the core will also mushroom.
All of this is well and good, but, considering the only solid brass bullet on the market is the Barnes X something, for pistols, you have only one choice, and, generally, the velocities are not enough to sheer off the 'petals', but, it does
create some fun ideas...
9mm has some specific problems, and advantages. 9mm ball tumbles, in gello, so, in people, hitting bones, etc. this is a design to create damage.
HP's may not penetrate enough, depending on the size of your bad guy, since even the best HP's are still around 12-14" of penetration.
Although as I understand it, whether or not it's worthwhile to reload 9mm ammo is a debate in and of itself. Sure would be fun though!