Could be something as simple as hook and loop tape. One side is permanently/semi-permanently affixed to the slide the other side gets swapped based on x criteria. That's how I'd do it. The military loves velcro.
True, but the photos don't seem to show the depth that hook-and-loop would add. That, and even the milimetre that hook-and-loop would add could impede draw and reholstering.
I was in a non-US military and we used electrical tape - two or three strips around rifle magazines.
I was in a non-US military and we used electrical tape - two or three strips around rifle magazines.