Robbins290
Member
When I purchased a Storm Lake 9mm conversion barrel for the M&P40 at Grabagun, the had a super offer for 9mm factory magazines. I purchased 2 of them. So I haven't tried using a 40/357 magazine with that barrel.
But now I'm curious to see if those magazines will work with the 9 next time at the range.
KC of ohio, I noticed with the M&P (full size anyways) that they need the 9mm mags. Mine will not cycle a full 17 rounds thru the mag without some kind failure to feed. I had plenty of 9mm mags so i had no issue. I had the opposite with the glock 22, ran like a sewing machine with the 40 mags.