Bought two of these. Not bad for the price, but I'm wondering if anyone else has encountered this problem: when the last round in the magazine comes up, the slide locks back as if the magazine was empty, and I have to push the slide lock button to chamber the last round. Very disconcerting, to say the least. Both of the ones I bought do this consistently. I guess they're OK strictly as practice mags to save wear and tear on Sigs excellent factory mags, but I would not have bought these if I had known about this.