9mm Major, also known as 9 Major, ammunition is loaded much hotter than typical 9mm rounds, exceeding  to achieve a power factor of 165. This classification benefits competition shooters as it allows maximum magazine capacity and scoring. However, it is not readily available and dangerous to use in pistols not designed for such high pressure. Most handgun manufacturers caution against using "+P" and "+P+" ammo, and 9mm Major loads generate even higher chamber pressures. The Taran Tactical "Combat Master" 2011 and similar pistols are designed for these pressures. In tactical situations, the added velocity may improve vest penetration, but it may hinder hollow-point projectiles' effectiveness due to over-expansion. Proper cartridge design is crucial for optimal performance.

The popularity of 9mm Major has risen due to the lower cost of 9×19mm Parabellum Luger cases compared to .38 Super cases, and the versatility of using guns designed for the shorter 9mm Luger cartridge. Competitive shooters in the Open Division often handload their ammunition to customize their loads for optimal performance. However, some ammunition manufacturers like Atlanta Arms, JJR Ammo, ORM Tech and Universal Ammo produce 9mm Major rounds with competitors in mind.

Sport shooting

9mm Major is a wildcat cartridge of the 9mm Luger specifically for competition pistols designed to handle very high pressure. It is used in practical shooting competitions like International Practical Shooting Confederation (IPSC) and United States Practical Shooting Association (USPSA) to achieve a "Major" power factor, which earns more points for hits in specific zones on paper targets compared to the "Minor" power factor. Power factor is calculated by bullet weight multiplied by velocity, divided by 1,000. To qualify for Major power factor in USPSA, the 9mm Major loads must reach higher velocities than standard factory 9mm Luger ammunition, making it suitable for competitive shooting but not readily available as commercial off-the-shelf ammunition.

The 9mm qualifies for Major scoring only in the Open Division of practical shooting competitions, where compensators and optical sights are permitted. Open Division guns, often called a racegun, are purpose-built for high-powered, high-speed competition and can handle the high pressure of 9mm Major and .38 Super ammunition. These guns feature ramped barrels that fully support the case head, ensuring safety with the high-pressure rounds. Not all gun designs can safely handle 9mm Major ammo, and many factory barrels may need to be replaced for better case support. 9 Major rounds operate at high pressures, typically at +P or even +P+ levels, necessitating careful gun design and appropriate gunpowder selection to ensure safety and optimal performance.

Most Open Division shooters prefer using  bullets for their 9mm Major loads. Lighter bullets require more gunpowder weight to achieve the necessary velocity compared to heavier bullets using the same gunpowder, resulting in more gas for the compensator. Brands like JJR Ammo, ORM Tech and Universal Ammo typically use  bullets in their 9mm Major ammunition. These loads provide impressive performance, but it's crucial to have the right gun and barrel design to handle the high pressures safely.

To ensure safety and compatibility, shooters must pay attention to the case support in their barrels, especially when using compensators or suppressors. Handloading allows shooters to adjust bullet weights and powder charges to suit their preferences and gun characteristics. Loading 9mm Major rounds as long as possible is common practice to keep peak pressure low. However, some flat nose bullets, such as hollow points, may cause magazine fitment issues if loaded to the maximum Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) overall length of . For example, Atlanta Arms rounds, loaded to  with hollow point bullets, and JJR and ORM ammo, while fitting in Glock magazines, may have slight rubbing against the front wall of the magazine.

Firearm compatibility

In the world of 9mm Major pistols, the majority are built on a 1911/2011 frame, originally designed to accept the longer .38 Super cartridge. These frames allow the use of longer-loaded 9mm Major ammunition, especially when not using spacers to convert them strictly to 9mm Luger ammo. Handloading offers the advantage of adjusting the length of the ammo to fit one's specific gun, magazine and chamber.

The Alpha Wolf barrel used for testing accommodated all rounds, but not all barrel chambers can handle 9mm Major rounds loaded at this length. Many racegun chambers have extended throats to support longer-loaded ammo, providing another reason why handloading is preferred for these specialty rounds.

References

See also
 9 mm caliber
 List of firearms
 List of handgun cartridges
 List of rifle cartridges
 Table of handgun and rifle cartridges

9mm Parabellum firearms
Pistol and rifle cartridges