What Is .38 Super Auto

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Last updated: April 10, 2026

Quick Answer: The .38 Super Auto is a high-powered pistol cartridge introduced in 1911 as an enhanced version of the .38 ACP, delivering muzzle velocities of 1,280-1,450 feet per second and approximately 400-500 foot-pounds of energy. It became particularly popular in competitive shooting sports during the 1970s-1980s and remains widely used in IPSC and USPSA competitions today.

Key Facts

Introduced in 1911 by Colt as an upgraded alternative to the .38 ACP cartridge to meet demand for greater power
Achieves muzzle velocities of 1,280-1,450 feet per second depending on bullet weight and powder charge, significantly exceeding .38 ACP performance
Generates approximately 400-500 foot-pounds of muzzle energy, making it suitable for both competition and defensive applications
Became the dominant cartridge in IPSC and USPSA competitive shooting during the 1970s-1980s competitive boom and remains popular in these sports
Uses the same frame and magazines as .38 ACP pistols but requires different barrels and recoil springs, making conversion between the two relatively straightforward

Overview

The .38 Super Auto (often called .38 Super or 9mm Super) is a pistol cartridge that emerged in 1911 when Colt developed it as a more powerful alternative to the .38 ACP. This cartridge was created to provide law enforcement and competitive shooters with higher velocity and stopping power while maintaining compatibility with existing .38 ACP pistol frames. The design proved successful, establishing itself as a favorite among serious competitors and defensive shooters.

Unlike the original .38 ACP, which generated relatively modest ballistic performance, the .38 Super Auto produces velocities approaching 1,400 feet per second with standard loadings. This significant performance increase made it attractive during the early competitive shooting era and contributed to its resurgence in popularity during the 1970s and 1980s when IPSC (International Practical Shooting Confederation) and USPSA (United States Practical Shooting Association) competitions began gaining prominence. Today, the .38 Super Auto maintains a dedicated following among competition shooters and remains available from major ammunition manufacturers worldwide.

How It Works

The .38 Super Auto operates on fundamental pistol principles, with specific characteristics that distinguish it from similar cartridges:

Cartridge Dimensions: The .38 Super uses a slightly longer case than the .38 ACP (0.900 inches versus 0.765 inches), allowing for greater powder capacity and higher pressures that generate superior velocities
Pressure and Velocity: Operating at approximately 36,500 PSI (pounds per square inch), the cartridge accelerates bullets to 1,280-1,450 feet per second depending on bullet weight and powder formulation, significantly exceeding .38 ACP performance
Bullet Compatibility: Standard .38 Super loads typically use 130-grain and 147-grain bullets, with common velocities reaching 1,400 fps for 130-grain projectiles and 1,280 fps for heavier 147-grain rounds
Energy Delivery: Muzzle energy ranges from approximately 400 foot-pounds with heavy bullets to 500+ foot-pounds with lighter projectiles, providing reliable energy for both target shooting and self-defense purposes
Magazine Compatibility: The .38 Super shares the same magazine as 9mm Parabellum in many pistols, though the cartridges are not interchangeable due to dimensional differences

Key Comparisons

Cartridge	Year Introduced	Muzzle Velocity (fps)	Muzzle Energy (ft-lbs)	Primary Use
.38 ACP	1900	900-1,050	200-280	Self-defense, historical
.38 Super Auto	1911	1,280-1,450	400-500	Competition, self-defense
9mm Luger	1902	1,150-1,300	350-450	Military, law enforcement, sport
.40 S&W	1990	900-1,050	350-500	Law enforcement, self-defense

Why It Matters

Competitive Shooting Dominance: The .38 Super Auto became the preferred cartridge for major shooting sports during the 1970s-1980s IPSC boom, where its superior velocity and accuracy made it ideal for steel target competitions that required reliable bullet performance
Performance Bridge: The cartridge successfully bridges the gap between weaker .38 ACP loads and more powerful cartridges like the .45 ACP, offering shooters a middle-ground option for both sport and defensive applications
Conversion Capability: Shooters could convert .38 ACP pistols to .38 Super with minimal parts changes—primarily barrel and recoil spring—making it economical for competitors to experiment with the cartridge
Ammunition Availability: Despite being less common than 9mm or .40 S&W, the .38 Super remains in production from major manufacturers, ensuring continued availability for competitors and enthusiasts

The .38 Super Auto represents an important chapter in firearms development, demonstrating how modest modifications to existing designs can create significantly improved performance characteristics. Its continued use in competitive shooting validates its ergonomic and ballistic capabilities, while its historical significance in competitive shooting sports ensures it will remain relevant for future generations of shooters who value proven performance and reliability.