.38 Super Automatic +P (Handloader issue #357)

The .38 Super Automatic traces its origins to 1929, when Colt introduced it as a higher-pressure improvement of the earlier .38 Automatic Colt Pistol (.38 ACP) cartridge introduced in 1900. While the two cartridges share nearly identical external dimensions, the .38 Super operates at significantly higher pressures and should never be fired in firearms designed solely for the older .38 ACP. Colt developed the cartridge to provide law enforcement with a semi-automatic handgun round capable of penetrating the steel automobile bodies and primitive body armor that had become increasingly common during the Prohibition era. Chambered initially in the Colt Government Model pistol, the .38 Super quickly gained a reputation for high velocity, flat trajectory, and excellent penetration.

Although overshadowed in the United States by the rise of the .357 Magnum and later the 9mm Luger, the .38 Super remained especially popular in Latin America, where military restrictions often prohibited civilian ownership of firearms chambered in military calibers. Its combination of mild recoil, excellent magazine capacity, and impressive ballistic performance made it an attractive choice for defensive pistols and competitive shooting alike. During the 1980s and 1990s, the cartridge experienced a resurgence in practical shooting competitions such as IPSC and USPSA, where its ability to make Major Power Factor with relatively low recoil gave competitors a distinct advantage. Modern pistols with fully supported chambers further enhanced both safety and performance.

In 1974, SAAMI officially redesignated the cartridge as the .38 Super Automatic +P to distinguish modern high-pressure factory ammunition from the older .38 ACP. Despite the "+P" designation, the cartridge is not simply an overpressure version of an existing round like many other +P handgun cartridges. Instead, the designation serves as a warning that modern .38 Super ammunition is loaded to substantially higher operating pressures than the original .38 ACP. Handloaders benefit from a wide variety of .355-inch bullets, abundant component availability, and powders capable of producing excellent velocity while maintaining outstanding accuracy. The cartridge's semi-rimmed case has also been refined over the years, with many modern competition barrels headspacing on the case mouth rather than the semi-rim for improved consistency.

More than ninety years after its introduction, the .38 Super Automatic +P continues to enjoy a loyal following among competitive shooters, defensive handgun enthusiasts, and handloaders. Its unique combination of high velocity, manageable recoil, excellent accuracy, and reliable feeding has ensured its continued relevance long after many cartridges of its era faded into history. Whether chambered in a classic Colt Government Model or a modern competition pistol, the .38 Super Automatic +P remains one of the finest high-performance semi-automatic handgun cartridges ever developed.

Source: Handloader Issue #357 – August 2025