Can we get over the randomized statistical circle jerk with this test already?
Quality means a fundamentally good design that performs well in its idealized implementation, prints that are complete and well-specified with all the functional features controlled well, materials well specified for the design with trustworthy certs, the microstructure of the metal in the intended condition, whether billet, cast or forged, correct heat treatment, tool wear managed so surface finishes are of the correct profiles, accurate machining and gauging, finishes that meet spec with minimal defects, good "fit and finish," etc.
MAC's "gauntlet" test is not a quality audit. Guns that do well in the test have full-length dust covers and outer rails that prevent the muck from sticking to the side of the slide and getting drawn back into the between-the-rails space and jamming it up. That is the difference that makes a difference for the Arex versus a genuine Sig. It's also logically helpful in the test if the "rails" are short little steel tabs with the forward most ones at least 1/3 of the length of the gun away from the front of the slide where the muck starts entering. Pistols that have both of these characteristics will do well. A Taurus that had those characteristics would do well, if something else didn't go wrong.