Finally got around to testing these. I bought 3. They all ran flawlessly through my 43x. The only negative thing I could point out is that they don't lock the slide on the last round but that's not much of a negative compared to the extra 5 rounds you get. These are quite the game changer. My 43x holds 15 rounds with a lower profile than my 19. My 19 of course can hold the 33 round mags, but this turns the glock 43x into the ultimate ccw imo. If I'm in a situation where the 43x is too large of a profile then I carry the LCP in pocket or IWB.