One of our local shooters ordered some “Promag” after-market S&W M&P magazines recently. His baseplates soon started popping off, dumping ammunition and magazine parts everywhere.
We took one of his mags home for a little inspection tour — and while the basepads were correct, the magazine tube was roughly .030″ too narrow.
We think this is simply a bad batch that got by the Promag QC people, so here’s the test: Push the baseplate all the way left or right, and see if a gap appears between the mag tube and the inside edge of the baseplate.
If you can see the lower lip of the magazine — you’ve got a problem. Check yours right away!