.950 JDJ

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.950 JDJ
Type Rifle
Place of origin  United States
Production history
Designer J. D. Jones
Manufacturer SSK Industries
Parent case 20×102mm Vulcan
Bullet diameter 0.950 in (24.1 mm)
Case length 4 in (100 mm)
Ballistic performance
Bullet weight/type Velocity Energy
3,600 gr (233 g) 2,200 ft/s (670 m/s) 38,685 ft·lbf (52,450 J)

The .950 JDJ is an extremely powerful very large caliber rifle cartridge developed by American gunsmith and weapon designer J. D. Jones of SSK Industries.


Loaded .950 JDJ cases are approximately the length of an empty .50 BMG casing (i.e., 4 in or 10 cm), and are based on a 20×102mm case shortened and necked up to accept the .950 in (24.1 mm) bullet.[1] Projectiles are custom-made and most commonly weigh 3,600 grains (230 g) which is 8.2 ounces or over half a pound.[2]


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 by a civilian 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 110 pounds (39 to 50 kg) and are therefore only useful for shooting from a bench rest or heavy bipod.[3] 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. Thus, they are largely "range queens"—i.e. rifles that are brought to the range primarily for a fun time and the sheer spectacle of it, but not usually used for hunting or other more practical uses.


The cartridge propels its 3,600 gr (230 g) bullet at approximately 2,200 ft/s (670 m/s). This yields a muzzle energy of 38,685 ft·lbf (52,450 J)[1] and a momentum of 154.1 Newton-seconds, about the same as a 20×102mm Vulcan round.[citation needed]

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 20mm 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. 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.

See also[edit]


  1. ^ a b McBros .95 caliber rifle, Airborne Combat Engineer.
  2. ^ Rifle ..., SSK Industries.
  3. ^ McBros 95 caliber rifle single-shot bolt-action rifle, Securityarms.com

External links[edit]