Many years ago (before Dun Blane) I held a firearms licence and had a couple of pistols. One of these was a S&W .357 Magnum.
Around the same time I worked at Gatwick airport and had to attend an anti-terror training session at the police station. This was when airports were one of the few places you would openly see armed police. During the session they talked about the weapons they used and the ammunition. Their advise at the time was if a situation occurred in the terminal buildings, get behind the plant pots as their ammunition was "soft" and low charge for the sole intention that it would not pass through the targeted terrorist and would splinter up causing massive internal injuries preventing the terrorist from doing anything other than dropping down dead.
I must admit, I did take the piss a little as my .357 was a genuine S&W model whereas the plod version was a cheap copy into which they were not allowed to use the magnum cartridges as they were deemed too powerful 
the MP5 they used at the time, and derivatives are still used now, have a significant range/accuracy advantage over a pistol with a 6" barrel so are the favoured weapon and the one used at all times unless they run out of ammunition on the MP5. Unfortunately, even the low powered ammo they use can still pass straight through a body at close range and unless it hits a bone, exits out the read of the body in one piece. It's a risk worth taking unless you are in a densely populated situation.
In my country (and most of Europe for all I know), 9 mm parabellum is the standard police pistol cartridge. Decent penetration, but not too much noise, flashing, and low risk of over-penetration (and hitting people behind obstacles). USA have a different policy as far as I know, using cartridges with better penetration, being able to go through a car door, arm, then through the chest to the heart.
Pistol ammo will hardly split up and cause massive internal injury - it's a moot marketing point IMO. High power cartridges from long barrels - yes, but not pistol ammunition. Unless you pierce the heart, or the brain/upper spine, "dropping dead" time depends on the target's mentality. However, I understand that airport police would use the ammo with minimal over-penetration ability, not for the purpose of criminals "dropping dead" more quickly, but to minimize risk of the police shooting injuring other people.
Personally, I'd love to see a law giving life sentence to anyone caught with a firearm, even if not doing any crime. Preventing firearm use to everyone, including the police (so criminals don't fear being shot at, and for that fear doing something even more stupid). Army and special task force to deal with terrorism and a few armed criminals. Maybe I'm too naive, but I think it would work.
