How many off you have had an M&P compact, or regular size M&P, fail to feed on the 9th round. I have an M&P40c with over 3000 rounds through it. Three time it has failed to feed with the slide open on the 9th round. I assumed I had caused the slide to lock when firing. It was always on the 9th round of the 10 round magazines. Today I may have found the problem. While unloading a magazines with my thumb, the brass cases started to jam against the top front of the magazines. It started on the 7th round and continued through the 9th round. All other rounds pushed out with no contact with the magazines front. This had happened before, but I didn’t connect it to a jam until today. I believe the 9th round is pushing forward bumping the top front of the magazine and jamming. Now I need it to fail again so I can verify this. I have four magazines and I relieved one by filing an angle like a knife blade on the magazine at that spot, Then I polished it with a felt buffer and red compound. Now when I push rounds out of that altered magazine with my finger, they bump, but they don't stop.
I have seen a couple of posting about this on this sight. Has anyone else had this happen and what conclusions have you come up with.
Phil

How many off you have had an M&P compact, or regular size M&P, fail to feed on the 9th round. I have an M&P40c with over 3000 rounds through it. Three time it has failed to feed with the slide open on the 9th round. I assumed I had caused the slide to lock when firing. It was always on the 9th round of the 10 round magazines. Today I may have found the problem. While unloading a magazines with my thumb, the brass cases started to jam against the top front of the magazines. It started on the 7th round and continued through the 9th round. All other rounds pushed out with no contact with the magazines front. This had happened before, but I didn’t connect it to a jam until today. I believe the 9th round is pushing forward bumping the top front of the magazine and jamming. Now I need it to fail again so I can verify this. I have four magazines and I relieved one by filing an angle like a knife blade on the magazine at that spot, Then I polished it with a felt buffer and red compound. Now when I push rounds out of that altered magazine with my finger, they bump, but they don't stop.
I have seen a couple of posting about this on this sight. Has anyone else had this happen and what conclusions have you come up with.
Phil

If it solves it, who are we to argue?
Can't count the number of seemingly wacky things I've seen over the years, that "worked".
I seem to recall a small item, about how many rounds to stuff into a certain rifles magazine at one time, and still have it run?

Mine isn't a compact but the full size 45 and I haven't had an issue with factory mags. I did have issues with after market mags, the springs aren't strong enough to work with the fast action of the pistol and I simply got rid of them. If you are using factory mags try and clean them and you will get better results.

Had the same problem. Cleaning did not help. Then noticed the snagging on mag. Filed front of mag lower. Problem solved.

No problems with either of mine (9 mm full size and compact). I have probably 11 magazines between the two and all have been flawless.

interesting... how do you clean a magazine?