The gun's entire upper assembly (barrel, cylinder and frame) are mounted on rails on the lower frame, which houses the trigger, hammer, and grip, and recoils 1/2 of an inch, or 12.7mm, on firing. The rearward motion of the upper assembly cocks the hammer, and the cylinder is rotated on the forward stroke. This unique action makes this revolver a semi automatic weapon, making it one of the very few semi automatic revolver designs, another notable design being the Webley–Fosbery Self-Cocking Automatic Revolver. The inclusion of the 454 Casull chambering makes the gun one of, if not the, most powerful semi-automatic handgun ever produced. This chambering places the Mateba in comparison to firearms like the Wildey pistol chambered in .475 Wildey Magnum and .44 Mag examples of the AutoMag pistol.