Let me say this about that..... I pushed 9mm rounds into my .40 Para mags and the rounds don't stay in. You might be able to bend the lips outward on a Beretta 9mm mag to get it to feed .40's correctly in a 96, but you also might screw it up hopelessly. Remember, the lips not only have to be the correct spacing to let the round feed, they have to be the correct height and angle to present the round to the feed ramp. One thing I know about the steel used in mag shells: it's pretty hard (read that brittle) and won't take much bending to crack.
