M&P Magazine Problem/Question

[Ironman8]

First I want to say thanks to Grant for a very smooth and quick transaction on my new FS M&P9. This was my first transaction with him, and will definitely buy from him in the future as well as steer some new business his way. So thanks Grant!

So on to my problem/question.

I have another FS M&P9 that I have had since 2008 (which I'm guessing is the manufacture year as well) along with 4 magazines that I got in the same time period. All have functioned perfectly and had no problems.

Fast forward to now, and I get the M&P from Grant along with 3 mags plus 2 mags from a different vendor. This makes a total of 9 mags (4 from 2008, and 5 from 2011).

As I was going through my inspections, I noticed that all mags inserted and seated very smoothly and positively into the new M&P, but the problem came with my older one. With my older M&P, my 4 older mags seated perfectly as usual (whether unloaded or loaded), BUT with the new mags, I noticed that they were just barely seating when empty. So I loaded them up to 17rds each, and 2 out of the 5 new mags JUST barely seated, but the other 3 wouldn't seat without forcefully slamming them in.

My question is, did S&W change anything (dimensionally or otherwise) to either the mags or the gun? I noticed the baseplate and follower are different, but to my naked eye, I can't tell a difference in dimension. Is this a problem with the mags or the gun? Is there any way to adjust the mag catch/release to make them seat more positively?

[1911-A1]

I"m not sure if you've tried this yet, but remove the floorplates, place them both on a flat surface, and hold a new mag back-to-back with a suspect mag, and see if there are any differences in the height of the feed lips, mag catch cut, etc.

[Thomas M-4]

If I memory is correct they changed something on the mag release.
Love the M&P but there for a few yrs they were changing stuff fairly often. I stopped keeping up with it all after the first frame revision.
Could be wrong maybe its something else but I do remember on the M&P forum S&W was changing to a different mag release.

[Urabus23]

I have a M&P 9(MPFXXXX) from around the same time and some new mags that were purchased this year. Both the old and new mags seat and run well.

Maybe you could try and leave the new mags loaded for a few days and see if it breaks in the springs.

Hope you get it sorted

[aziator]

I have a M&P 9(MPFXXXX) from around the same time and some new mags that were purchased this year. Both the old and new mags seat and run well.

Maybe you could try and leave the new mags loaded for a few days and see if it breaks in the springs.

Hope you get it sorted

I would try this. It may just be the spring is stiff pushing up on the follower. The mags that came with my 9L that I purchased this year fit perfect in my wife's M&P9 that she purchased back in 2006.

[jwperry]

My more recently purchased M&P mags have much flatter floor plates than my older ones. It doesn't matter to my pair of pistols, but the floor plate dimensions might matter to yours.

[Ironman8]

Well I figured out the problem.

I was just about to respond to 1911 about checking the difference between the mags without the baseplates on, when I remembered that the baseplates are the only things I didn't check! Sure enough, the "lip" of the baseplate that contacts the bottom of the magwell (when the mag is seated) is raised higher on the newer designed baseplates than on the old ones. This prevents the mag from locking in to the mag catch/release by maybe a 1/16"...I guess there is also a slight dimensional difference between the old and new guns when it comes to the height of the mag catch/release as well since both old and new baseplates lock into the new gun...

Hopefully S&W has some old style baseplates they can send me...

[Ironman8]

My more recently purchased M&P mags have much flatter floor plates than my older ones. It doesn't matter to my pair of pistols, but the floor plate dimensions might matter to yours.

Its the other way around for mine...