The .50 Action Express was developed in 1988 for the IMI Desert Eagle semi-auto pistol. Designed by Evan Whildin, it featured a rim essentially identical in diameter to the .44 Magnum while the case head was notably larger, measuring .543 inch, making it a rebated case. Overall cartridge length was slightly shorter (.015 inch) than the .44 Magnum, all of which allowed it to function in the Desert Eagle with nothing more than a barrel change. For reference, Speer Gold Dot 325-grain UHP factory loads averaged 1,454 fps.

Although the Desert Eagle has been successful, the .50 AE often appears in revolvers such as the Freedom Arms Model 83 and Magnum Research BFR. The accompanying test data was developed in a BFR, which yielded similar velocities as the Desert Eagle. Correct bullet diameter is .500 inch, the same as the .500 S&W, and should not be confused with bullets for the .500 Linebaugh and similar cartridges that utilize .510- to .512-inch bullets.

Although the case has significant taper, it headspaces on the case mouth. Loads in the accompanying data were taper-crimped to .523 inch after bullets were seated to correct overall length, which is the same measurement used in Speer and IMI factory loads.

Winchester Large Pistol (WLP) primers were used. This particular primer produces the least energy (gas volume and heat) when compared to other large pistol primers. Although data that illustrated poor ignition qualities with ball powders was eliminated, if ignition seems erratic in any way, or if used in extreme cold temperatures, it is suggested to switch to a Remington 2 ½, Federal 155 or CCI 350 primer, all of which will offer greater ignition qualities.

The cast bullet data is primarily intended for revolvers; however, if used in a Desert Eagle pistol, the overall cartridge length should be decreased to 1.580 inch.

Depending on the pressure curve and gas volume, many of the "start" loads will not generate enough energy to cycle the action of the Desert Eagle. And the faster burning powders such as Accurate No. 7, Hodgdon Longshot and Alliant Power Pistol are intended primarily as reduced and mid-range loads for revolvers only. Maximum loads with No. 7 and Longshot however, functioned fine in our test pistol.

Maximum average pressure limits are 35,000 psi, and none of the loads herein exceed that figure.