The Desert Eagle ...

"The Desert Eagle" was originally designed by Bernard C. White of Magnum Research, who filed a US patent application for a mechanism for a gas-
actuated pistol in January 1983. This established the basic layout of the Desert Eagle. A second patent application was filed in December 1985, after the basic design had been refined by IMI (Israel Military Industries) for production, and this is the form that went into production. The Desert Eagle uses 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. When a round is fired, gases are ported out through a small hole in the barrel near the breech. These travel forward through a small tube under the barrel, to a cylinder near the front of the barrel. The separate bolt carrier/slide has a small piston on the front that fits into this cylinder; when the gases reach the cylinder they push the piston rearward. The bolt carrier rides rearward on two rails on either side of the barrel, operating the mechanism. Its 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. Thus 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.