James Tarr over at Handgunsmag.com explains why Defensive Handgun Ammo is better now.
1. FBI Ballistic Test Protocol. Due to the FBI 1986 Miami Shootout, a standardized test was created by the FBI to test the effectiveness of defensive ammo. This FBI Protocol has become the industry standard for testing ammo.
2. Better Powders. A lot of focus and attention is given to the bullet. Look at the recent intrigue regarding the G2 RIP bullets. The powders used now not only increase velocity but they manage to keep muzzle flash low. Many calibers can be found to have ballistic performance similar to the next larger caliber in the line. For example, some .380 is seeing velocities similar to a 9mm.
3. As mentioned above, Better Bullets. More engineering goes into designing hollowpoints to achieve more reliable expansion.
4. Quality Control. Modern optical scanners, laser gauges and every high-tech scanner and tool you can think of is used to ensure that the ammo produced is as close to perfect as possible. CNC machines are now also manufacturing the dies that ammunition companies use instead of humans, which results in closer tolerances.