In 1908, Colt introduced the 380 Automatic Colt Pistol (ACP). This compact round has an intermediate working pressure, which combined with modest capacity and bore size limits fight-stopping effectiveness. On the positive side, compared to the 9mm Luger, in guns of similar size and weight the 380 is much easier for most shooters to learn to use well. The 380 can be chambered in much smaller and far lighter guns. The original guns were all blowback-operated and therefore required a relatively heavy slide and barrel assembly. Modern, locked-breach, guns can use much lighter components. This allows guns as light as seven-ounces! As such, several manufacturers now make 380 pistols that are so light and compact many professionals carry two or three as emergency backup guns. Best modern ammunition has bullets that perform well, considering the limited energy available. The modest working pressure will always limit performance. Necked-down rounds based on the 380 ACP case use higher working pressure and can therefore deliver more energy with lighter bullets launched much faster and do so while generating similar recoil. I worked with Cor-Bon on a 32-caliber version. It used the same pressure as the 9mm Luger and offered significant performance. Cor-Bon did not pursue that round but other manufacturers have pursued similar designs. A version in 25-caliber was standardized at one time. As with any pistol round headspacing on the case mouth, best practice is to apply a taper-crimp after seating the bullet. This helps to lock the bullet in place against chambering forces that might otherwise drive it into the case. I cannot too-strongly recommend getting a second seating-and-crimping die so you can have one adjusted to seat the bullet and the second adjusted to only taper-crimp the case mouth. Generally, attempting to do both operations in one step is a recipe for damaged and destroyed cases.