The Desert Eagle was originally designed by Bernard C. White of Magnum Research, who filed a patent on a mechanism for a gas-actuated piece in January of 1983. This established the necessary layout of the Desert Eagle. It consisted of a gas-operated mechanism normally found in rifles, as opposed to the short react or blow-back designs most commonly seen in semi-automatic pistols. A second patent was filed in December of 1985, after the basic layout had been refined by IMI for production, and this is the form that went into production.
The Ink 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 assurance levers and fall off catch. The Autograph VII includes an adjustable trigger (retrofittable to Mark I pistols). The John Hancock I and VII are both come-at-able 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 http://www.gunslot.com/guns/magnum-research-desert-eagle attached. Later Mark VII models were offered in .50 Action Express with a 7/8" Weaver-pattern rail on the barrel; the .50 Impression VII would later become the Impression XIX platform. Tun lengths were 6, 8, 10 and 14 inches.