The .375 JDJ (J.D. Jones) is a high-powered, wildcat rifle cartridge developed by J.D. Jones of SSK Industries. It is essentially a .444 Marlin case necked down to accept a .375 caliber bullet. Designed for use in single-shot rifles and handguns, particularly the Thompson/Center Contender, the cartridge is favored for its potent performance.
The .375 JDJ is renowned for its versatility and impressive ballistics, making it suitable for both big game hunting and metallic silhouette shooting. It can effectively take down medium to large game, including deer, elk, and even African plains game, thanks to its high muzzle energy and deep penetration characteristics. The cartridge typically fires a bullet weighing between 200 and 300 grains, with muzzle velocities ranging from 2,000 to 2,400 feet per second, depending on the load.
Given its origins as a wildcat cartridge, handloading is a common practice among .375 JDJ users, allowing them to tailor loads for specific purposes and performance characteristics.
Overall, the .375 JDJ is a powerful, versatile cartridge known for its effective performance in both hunting and shooting sports.