I have two of the new style mags in 9mm, one of them ran fine out of the box and the other needed the spring bent to prevent nose dives. I've only put 250 rds through each of them and I haven't had any problems since bending the spring in #2. I will say the mag that was giving me nose dives has a lighter spring than the trouble free mag, and the feed lips are tighter at the front than the other one, .350 compared to .353. I'm using them in a very tight new CK thunder, and I'm going to order the Dawson mag tuning kit to get them perfect.