Very few guns are as captivating as the .950 JDJ, or “Fat Mac,” as it is more dramatically referred to. The .950 JDJ is not just any large-bore rifle; it ranks among the most daring and eccentric creations of small arms history. It has recently proven at Rock Island Auction Company’s Sporting & Collector Auction in Texas, where it fetched just under $100,000, that its myth keeps on attracting collectors and enthusiasts.
The ammunition is largely responsible for the mysterious aura surrounding it. The .950 JDJ had to be of a new breed with the Vulcan 20×110mm case, which was modified. The design of JD Jones was to neck the cartridge and reshape it to fit a .950-inch bullet, thus creating a cartridge that outshines even the .50 BMG in terms of size. Each bullet weighs 3,600 grains, that are about five times heavier than a .50 BMG round, and the cartridge itself is nearly four inches tall. In layman’s terms, this is a rifle that cannot be categorized with any other.
It was no less a problem to construct a gun that could hold such colossal power. To withstand extreme pressures, rifles were designed with thick McMillan-style stocks and heavy Krieger bull barrels. The muzzle brake, which only weighs 18 pounds, is a must-have for this kind of violent recoil.
The Fat Mac reaches a weight between 61 and 110 pounds, depending on how it was made, and in any case, it is a bench-rest rifle only. Still, the recoil is a nightmare – over 200 foot-pounds, which is more than ten times stronger than that of a .30-06 hunting rifle. To safely shoot it, the shooter must have reinforced optics, a solid bipod, and a really good shooting rest.
The figures it produces are equally impressive. 3600-grain bullets exit the barrel at a velocity of about 2200 feet per second; thus, the energy at the muzzle is around 38,000 foot-pounds. That makes it more or less equal to the shells discharged by the first tank guns of World War I era, but it’s three times more powerful than one of these .50 BMG. However, the great size and power of the round have been obstacles in its getting any kind of military use. The reasons are that it is simply too powerful to be of any practical use.
From a legal point of view, the rifle is a strange thing. Typically, firearms that have a diameter of more than half an inch are categorised as Destructive Devices under the National Firearms Act, meaning they are heavily restricted.
However, the .950 JDJ is considered a normal rifle due to a “Sporting Purposes Exception” granted to SSK Industries, that is, it is not a Destructive Devices category. This implies that any person who is legally qualified to possess a firearm can buy one without other regulatory steps.
While the Fat Mac shows engineering excellence, the owner must have known that he had a wonder, not a tool. It is definitely not a gun for the backcountry because of its weight, and the kick is severe even from a supported rest.
The price only adds to its rarity – rifles can cost well over $8000 while each custom-made cartridge can sell for $40 or more. Thus, to the major part of its owners, it is a showpiece, something that is fired at the range from time to time more for its spectacle than for its purpose.
Still, in the world of guns, .950 JDJ has made it to the level of legends. The name says it all: the one who doesn’t care about the boundaries and merely does it is exactly why it is sometimes called a “monster truck of rifles” – noisy, huge, and magnificently excessive.
And that is the only reason it survives. Not because it would have been in the front line of a battle, but because it was the purest definition of an assault weapon designed to be fired from the shoulder that was broken by it.