A quick glance at 9mm Major, the slightly larger older sibling of the 9mm Luger.
Debates arise regarding whether the 9mm Major is merely an amped-up 9mm Luger load or a distinct chambering firing 9mm bullets. It’s neither a wildcat cartridge nor a proprietary load; its unique OAL measurement makes it suitable for some firearms while unsuitable for others.
Some manufacturers provide special packaging for 9 Major loads, and it is risky to use 9mm Major ammunition in many standard handguns designed for 9mm Luger rounds, necessitating clarity.
Standard 9mm Luger ammo adheres to SAAMI specs of about 32,000 psi chamber pressure, resulting in velocities ranging from 850 to 1,200 fps, depending on the projectile weight. Contrarily, 9mm Major ammunition is loaded to achieve a Power Factor of 165 in IPSC or USPSA competitions. The power factor is calculated by multiplying bullet weight by velocity and dividing by 1,000.
To meet the major power factor in USPSA Open Division competitions, a 115-grain bullet must reach 1,435 fps, a 124-grain bullet must reach 1,331 fps, and a 147-grain bullet must reach 1,123 fps. Comparatively, 9 Major loads are approximately 200 fps faster than 9mm Luger loads of the same weight.
It is crucial to note that firing 9mm Major ammunition in a pistol not designed for the extreme pressures generated by such velocities can be hazardous. Many firearm manufacturers caution against using +P and +P+ ammunition, as 9mm Major loads can produce pressures exceeding +P+, rendering them unsafe for most conventional pistols.
Typically, only competition handguns are engineered to handle such elevated pressures. The primary feature in Open guns is a ramped barrel providing complete case head support. Non-ramped barrels or those with large cutouts for the feed ramp are unsuitable for 9mm Major ammunition.
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There’s no defined pressure limit for 9mm Major as a wildcat round. Careful gunpowder selection is essential when handloading. Only medium- to slow-burning-rate pistol powders are recommended as they produce lower peak chamber pressures when propelling the bullet at similar velocities to faster-burning powders. Atlanta Arms, in its 9mm Major listing, emphasizes, “Warning: This ammunition EXCEEDS SAAMI Specification and should only be used through a competition race gun.”
Most 9mm Major rounds are loaded as long as possible to maintain lower peak pressure. The SAAMI maximum overall length for the 9mm Luger cartridge is 1.169 inches. Black Dot Ammunition based in Crawford, Alabama loads its 9 Major rounds to an overall length of 1.160 inches, ensuring the ammunition “will not chamber in most standard 9mm guns to prevent accidental firing from non-open type firearms.”
Various manufacturers produce 9 Major ammunition, including JJR Ammo, C&S Ammo, Everglades Ammo, Vantage Reloading, and Universal Ammo.
Editor’s Note: This article is an excerpt from Gun Digest’s Cartridges of the World.
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