No, no marks at all on the two mags. that came with my example. The mag. with the finger extension looks like the machine marks (striations) on the back of the magazine (like in your photo) were polished slightly where the shoulder of the magazine begins. Looks like it was done prior to blueing. So, the answer is that my magazines show no wear after 200 rounds. The mag. in that photo really looks like something is very wrong. Didn't he use quite a few magazines for his video?