I had problems with the 17 round Mec Gars. For casual use they were fine, but on the last trip out to The Hun Farm, they had problems. I planned to give them a torture test anyway. I put them in the bed of my truck overnight, and they were covered in dew the next morning. I loaded the mags up and fired 17 rounds from each one, and all of them failed to lok the slide back. Well thats not a big deal, but we went rabbit chasing that night, and while driving around in the hun farm, the mags were coated inside and outside in that fine red dirt. 3 of the 6 mags had feeding problems. Ammo used was Blazer 115gr FMJ.
Now the 15rd mags were a different story, as they functioned flawlessly through my same test the next night. They were a mixture of the new Mec Gar 15rd mags and older SIG "zipperback" mags.
The 20rd mags functioned flawlessly as wel, Sunday night.
This is why I'm going to stick with 15rd P226 mags for both my P226 and P228, and the 20rd mags for both. Those Freeds X-Grip enhancers sure do make my P228 feel good.