The Desert Eagle was originally designed by Bernard C. White of Magnum Research, who filed a patent on a mechanism for a gas-actuated pistol in January of 1983. This established the basic layout of the Desert Eagle. It consisted of a gas-operated mechanism normally found in rifles, as opposed to the short recoil or blow-back designs most commonly seen in semi-automatic pistols. A second patent was filed in December of 1985, after the basic design had been refined by IMI for production, and this is the form that went into production.

From a functional perspective, the Desert Eagle is more like a small rifle than a pistol. The Desert Eagle's rotating bolt strongly resembles that of the M16 series of rifles, while the fixed gas cylinder/moving piston resemble those of the Ruger Mini-14 carbine (the original patent used a captive piston similar to the M14 rifle). The advantage of the gas-operation is that it allows the use of far more powerful cartridges than traditional semi-automatic pistol designs, and it allows the Desert Eagle to compete in an area that had previously been dominated by magnum revolvers. Downsides of the gas operated mechanism are the large size of the Desert Eagle, and the fact that it discourages the use of unjacketed lead bullets, as lead particles sheared off during firing could clog the gas release tap, preventing proper function.

Switching a Desert Eagle to another chambering requires only that the correct barrel, bolt assembly, and magazine be installed. Thus, a conversion to fire the other cartridges can be quickly accomplished. The most popular barrel length is 6 in (152 mm), although 8, 10 and 14 in (202, 254 and 356 mm) barrels are available. The Mark XIX barrels are machined with integral scope mounting bases, making adding a pistol scope a simple operation.

The Desert Eagle is fed with a detachable box magazine. Magazine capacity is 9 rounds in .357 Magnum, 8 rounds in .44 Magnum, and 7 rounds in .50 AE. The Desert Eagle's barrel features polygonal rifling. The pistol is mainly used for sport, target shooting, and hunting.

There are three variants to the Desert Eagle.

Mark I and VII

The Mark I, no longer produced, was offered with a steel, stainless steel or aluminum alloy frame and differs primarily in the size and shape of the safety levers and slide catch. The Mark VII includes an adjustable trigger (retrofittable to Mark I pistols). The Mark I and VII are both available in .357 Magnum and .44 Magnum; the Mark VII was also chambered for .41 Magnum. The barrels had a 3/8" dovetail, to which an accessory mount could be attached. Later Mark VII models were offered in .50 Action Express with a 7/8" Weaver-pattern rail on the barrel; the .50 Mark VII would later become the Mark XIX platform. Barrel lengths were 6, 8, 10 and 14 inches.


Mark XIX

The most recent model, The Mark XIX, is available in .357 Magnum, .44 Magnum, and .50 Action Express (or .50 AE). Magnum Research also showed some models in .440 Cor-bon caliber, a .50 AE derived case, but no .440 Cor-bon components are listed in their catalog and the .440 seems to have gone the way of the .41 Magnum. Mark XIX barrels are available in 6 and 10 inch lengths only.

While IMI makes a cosmetically similar pistol, originally called the Jericho 941 and now marketed by Magnum Research as the "Baby Eagle", the guns bear no functional equivalence—the Jericho/Baby Eagle design is a standard double action, short recoil design. The one functional similarity is in the IMI developed cartridges. The .41 Action Express (or .41 AE) developed for the Jericho 941 used a rebated rim, so that the pistol could switch between 9 mm Luger and .41 AE with just the change of a barrel. This is because the .41 AE was based on a shortened .41 Magnum case with the rim and extractor groove cut to the same dimensions of the 9 mm Luger. This allowed the same extractor and ejector to work with both cartridges. The .50 AE has a similar rebated rim, cut to the same dimensions as the .44 Magnum. This is what allows caliber changes between .44 Magnum and .50 AE with just the change of the barrel and magazine.

The Jericho 941 was named so for the two cartridges it chambered with the conversion kit.