That's what I was wondering. Makes sense. Sounds like an improvement. I'll be taking notice now when I'm looking for mags.Of my four mags, they measure about 0.484 inches without the bump and 0.518 with it. It clearly widens the mag at that point and holds it to the left a small amount and eliminates some wiggle. It does align the round to be fed more closely to the center of the feed ramp!
I don't want to put to fine a point on this but a Shield is an M&P. I am guess you are asking if a larger mags will work in the Shield. No, the Shield mags only work in the Shield. The larger fulldsized and compact won't go in the Shield.Will M&P mags work in Shield?