Full Name JD Jones | Name J. Jones | |
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Occupation Inventor, gunsmith, businessman | ||
J. D. Jones (born November 21, 1936) is an American firearms and cartridge designer, firearms writer and president of SSK Industries. Jones began hunting at an early age, and became interested in bullet casting and handloading firearms cartridges. In the 1960s, Jones collaborated with Lee Jurras to create the Super Vel line of high-performance handgun ammunition.
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In 1977, Jones founded SSK Industries, a company focused on cartridges and barrels (such as for the Thompson Center Arms Contender rifle-calibre pistol) for high-power handgun hunting and target shooting.
Jones is primarily known for two lines of firearms cartridges. The first is his line of JDJ cartridges, primarily intended for the T/C Contender, ranging from .224 to .577 calibre. The second is his "Whisper" family of cartridges, intended to cause maximum damage at subsonic speeds, making them nearly silent when used with a firearm suppressor.
Jones is a Life Member of the National Rifle Association and Safari Club International and is a staunch advocate of the Second Amendment. He has authored two columns for American Handgunner magazine.
.950 JDJ
The .950 JDJ (24.1x70mm) is a powerful large caliber rifle cartridge developed by American gunsmith and weapon designer J. D. Jones of SSK Industries.
Cartridge
.950 JDJ cases are approximately 70 mm in length, and are based on a 20×110mm case shortened and necked up to accept the .950 in (24.1 mm) bullet. Projectiles are custom-made and most commonly weigh 3,600 grains (230 g) which is 8.2 ounces or over half a pound.
Rifles
As its name implies, rifles chambered for the cartridge have a groove diameter of 0.950 in (24.1 mm). SSK received a "Sporting Use Exception" to de-regulate the rifles. Thus, in the United States, they can be purchased and owned like any other Title I rifle by an American citizen at age 18. The rifles use McMillan stocks and extraordinarily thick Krieger barrels bearing an 18 lb (8.2 kg) muzzle brake. Overall, depending on options, the rifles weigh from 85 to 120 pounds (39 to 54 kg) and are therefore only useful for shooting from a bench rest or heavy bipod. Despite the weight, recoil is significant and shooters must be sure to choose components (i.e., scopes and bipods) that can handle the abuse. The sheer size, weight, and power of these rifles make them rather impractical for hunting use. SSK only manufactured three of these rifles and as of 2014 no longer produces the ammunition.
Ballistics
The cartridge propels its 2,400 gr (160 g) bullet at approximately 2,100 ft/s (640 m/s). This yields a muzzle energy of 38,696 ft·lbf (52,465 J).
By comparison, the 5.56×45mm NATO cartridge, used in the M16 rifle, produces between 1,200–1,300 ft·lbf (1,600–1,800 J), while the .308 Winchester, a favorite for hunters and medium-range police/military sniping, produces between 2,000–3,000 ft·lbf (2,700–4,100 J) depending on the load used. The ballistics of the .950 JDJ are more similar to that of the 20 mm autocannon round, which delivers approximately 39,500 ft·lbf (53,600 J). The muzzle energy of the .950 JDJ is comparable to the kinetic energy of a 2,800 lb (1,300 kg) automobile traveling at 20 mph (32 km/h).
In a 110 lb (50 kg) rifle, this will develop well over 200 ft·lbf (270 J) of free recoil energy if an efficient muzzle brake is not used, roughly equivalent to the muzzle energy of a .380 ACP round. This is far beyond the shoulder-firing capacity of nearly all humans, even without considering the difficulty of shouldering such a heavy rifle. Shooting usually involves a heavy "lead sled" or similar shooting rest, and the rifle is not held to the shoulder because of the severe recoil and possible injury. The rifle scope has significant eye relief to avoid injuring the ocular orbit.