9 x 25 Dillon

The 9×25mm Dillon is a pistol wildcat cartridge developed for use in USPSA/IPSC Open guns. The cartridge is made by necking down a 10mm Auto case to 9 mm. Around 1987, Randy Shelley, an employee of Dillon Precision, necked down 10mm Auto brass to 9 mm. His goal was to get as much slow-burning powder in the case as possible in order to drive a 9 mm bullet to the velocity needed to qualify for the then-IPSC major power factor of 175. The short-necked and steep-shouldered cartridge holds twice the powder of a .38 Super Auto case. The 9×25mm Dillon was used by several notable IPSC shooters, such as Rob Leatham and Jack Barnes. Most shooters, looking at the 9×25mm Dillon today, focus on the extreme velocities of which it is capable. A 115-grain bullet at 1,800 fps is more than is needed for competition. There, a 115 only needs to be going a bit over 1,500 ft/s to qualify for major power factor. Competitors in the late 1980s and early 1990s who were using the 9×25mm Dillon used the additional powder available over .38 Super to produce more gas in the compensator, or muzzle brake, to make pistols shoot with as little muzzle rise as possible to allow faster follow-up shots on target. A muzzle brake works by diverting gases perpendicularly relative to the barrel to reduce felt recoil. The greater the gas volume, or the pressure that gas is at, the more force the compensator or muzzle brake creates. Competitors could "feed" a compensator more gases than comparable .38 Super loads. However, the muzzle blast also increased significantly, and the resulting recoil re-direction could be excessive with reports of some loads causing compensated pistols to recoil downwards.