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Hi folks



Anyone having a problem with your slide closing after the last round in the mag? Sometimes with my MP9 the slide wont remain open on the stop, other times the slide will close when I put a fresh clip in and slap it home I've shot about 600 rounds with it and I proberly saw this happen after somewhere around the 200th round. I use CPRN reloads indoors and Wincherter Range outdoors. Condition occurrs w/ both



Thanks
 

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Welcome to the M&P forums!



I have not had the first issue you mention, but after much reading, many have suggested that the slide stop lever is subject to be "bumped" by your thumb as the pistol is returning from recoil. You might want to try shooting with your other hand and see what happens. Also, pay particular attention to where your hand(s) are in relation to the lever when shooting. Maybe even let someone else toss a few rounds down range with your pistol...I would be glad to do this for you if you are near JVille, Fl....




Having the slide close when you slap the magazine in is very common with auto pistols. Every one I have owned, with the exception of my Ruger Mark I (no slide lock...lol), has done this at one time or another.



Hope you get it figured out and good luck!
 

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Are you experiencing the slide not staying back on more than one magazine? The spring of the magazine forces the follower up against the magazine catch so that it is elevated high enough after the last casing ejects to catch the slide as it moves forward. Either your thumb is bumping the slide catch keeping it from moving as far up as possible, your magazine spring/follower are failing to fully extend to the top of the magazine and not putting enough upward force on the mag catch, or the mag catch tab that the magazine's follower presses up against could be bent (this is rare), or the mag catch itself and/or the notch on the slide where the mag catch is supposed to hook up are worn (even more rare unless you've got a lot of rounds down the pipe and make a habit of releasing the slide with the magazine catch release).



If you are only experiencing the problem with a particular magazine, you've likely identified that magazine as the problem. There are gray followers available to replace the black ones for the 9mm magazines, and based on my reading on here, it sounds like they sit much higher in the magazines. I can't figure out if they are also recommended for use in 40 magazines (although one of the aftermarket shops -- IIRC brownells -- lists the same part number for 9, 40 and 357sig). If any magazine you try is doing it, you've likely eliminated the magazines as the source of the problem and should check your grip and the catch itself.



Good luck,
 

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The condition you describe is pretty common in auto pistols, I've probably encountered it most on my 1911's, they will fail to lock the slide back about 50% of the time, most other pistols are better at that than my 1911's, my M&P usually locks back, but it isn't 100%, probably like 95% on the M&P.
 

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MDuBois1 said:
Hi folks



Anyone having a problem with your slide closing after the last round in the mag? Sometimes with my MP9 the slide wont remain open on the stop, other times the slide will close when I put a fresh clip in and slap it home I've shot about 600 rounds with it and I proberly saw this happen after somewhere around the 200th round. I use CPRN reloads indoors and Wincherter Range outdoors. Condition occurrs w/ both



Thanks


Happens on mine as well. Has nothing to do wsith you fingers hitting the slide stop release. If I slap a mag in the slides pops forward. So you need to be careful if the clip has live rounds in it. Not sure if its a benefit or a con. : :?
 

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MDuBois1 said:
Hi folks



Anyone having a problem with your slide closing after the last round in the mag? Sometimes with my MP9 the slide wont remain open on the stop, other times the slide will close when I put a fresh clip in and slap it home I've shot about 600 rounds with it and I proberly saw this happen after somewhere around the 200th round. I use CPRN reloads indoors and Wincherter Range outdoors. Condition occurrs w/ both



Thanks


Happens on mine as well. Has nothing to do wsith you fingers hitting the slide stop release. If I slap a mag in the slides pops forward. So you need to be careful if the clip has live rounds in it. Not sure if its a benefit or a con. : :?
 

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Solved: M&P fails to lock back

My brand new M&P Pro 5" started failing to lock back on its second magazine. After calming myself -- this is my 4th M&P -- I started studying the problem as if it was a 1911 problem: possible causes, mechanical interference, vibration, etc. What I found was that the slide stop thumb grip was binding on the frame on the left hand side. I could see a slight scuff on the frame under the thumb grip when I pushed it up. A small amount of Brownells Gun Oil solved the problem in the short term, but, for reliability, I needed a permanent fix.

A week or to later, my Apex trigger kit arrived, giving me the opportunity to tear down the frame. What I found was that slide stop is made out of stamped steel, bent to shape. This creates a small radius bend on the inside of the "u-bend," where the stop tab is, and where the left thumb grip loops over the frame.

The frame itself, however, has a stamped steel stiffener on the inside of the polymer overmolding. Where the slide stop loops over it, that edge is quite squared off. When the slide stop dropped to its fully lowered position, this squared edge wedged against the radius bend of the slide stop, forcing the thumb grip against the frame.

Once I had found the source of the problem, the fix was simple: brief application of a 0.125" round stone on a Dremel, finished with a file, to radius the edge of the steel frame stiffener to match the inside radius of the slide stop bends.

I should have taken pictures while I had the gun torn down, but...now this one works like all the rest...flawlessly!

--j
 

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The condition you describe is pretty common in auto pistols, I've probably encountered it most on my 1911's, they will fail to lock the slide back about 50% of the time, most other pistols are better at that than my 1911's, my M&P usually locks back, but it isn't 100%, probably like 95% on the M&P.
None of my three M&P's or my seven 1911's fail to go to slide lock when the mag is empty.
 

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My brand new M&P Pro 5" started failing to lock back on its second magazine. After calming myself -- this is my 4th M&P -- I started studying the problem as if it was a 1911 problem: possible causes, mechanical interference, vibration, etc. What I found was that the slide stop thumb grip was binding on the frame on the left hand side. I could see a slight scuff on the frame under the thumb grip when I pushed it up. A small amount of Brownells Gun Oil solved the problem in the short term, but, for reliability, I needed a permanent fix.

A week or to later, my Apex trigger kit arrived, giving me the opportunity to tear down the frame. What I found was that slide stop is made out of stamped steel, bent to shape. This creates a small radius bend on the inside of the "u-bend," where the stop tab is, and where the left thumb grip loops over the frame.

The frame itself, however, has a stamped steel stiffener on the inside of the polymer overmolding. Where the slide stop loops over it, that edge is quite squared off. When the slide stop dropped to its fully lowered position, this squared edge wedged against the radius bend of the slide stop, forcing the thumb grip against the frame.

Once I had found the source of the problem, the fix was simple: brief application of a 0.125" round stone on a Dremel, finished with a file, to radius the edge of the steel frame stiffener to match the inside radius of the slide stop bends.

I should have taken pictures while I had the gun torn down, but...now this one works like all the rest...flawlessly!

--j
Just a friendly FYI to all; always modify/"work on" the cheapest part when doing gun work.

I would have opened up the slide lock "groove" just a bit, rather than filing on the frame.

The parts are cheap. The frame isn't; actually, you can't buy a replacement frame.

AFAIK, S&W won't sell frames (without all the rest of the parts attached; AKA the M&P pistol).
 

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I tried to resist, but it just got used one too many times.
Yep. It's embarassing to see this kind of ignorance, introduced by liberals in the media and government (who redefined semi-auto sporting rifles as "assalt weapons" and "military style weapons"), in a firearms related forum, by folks who should really know better.
 

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I've experienced the lack of slide locking back on my Shield in the past. At first I thought it was a magazine problem but soon realized that I was getting inconsistent results with all my mags.

It wasn't until a friend of mine recommended that I modify my grip and move my thumb away from the slide\slide release area that the problem went away.

That is where my testing ended. I was happy that the problem was gone and I didn't do anything more to verify if my thumb or the magazines were the culprit. But I have shot nearly 1,000 rounds through the Shield since I moved my thumb with not another incident of the slide lock problem. I have roughly 2,500 through it at this point.
 

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I purchased a used MP 40 that occasionally two of the three mags would not hold the slide open when m/t most of the time, after some investigation I found the spring in the mag was weak, so I removed the base plate tried to spread the spring out a little to increase tension on the follower after which no more problems with the slide stop. I went to the range yesterday and all went perfect, well the night sights are junk but I'm working on that.
 

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I bought my MP9 at the end of April and have had it at the range 3 times so far. The first 2 times there were absolutely no problems with the pistol. This past weekend I ran about 200 rounds through it and had the slide fail to lock open either 3 or 4 times. I have 4 magazines and reloaded twice. I didn't keep track of the magazines but I know the problem was with multiple magazines and not just one. I did shoot a couple of boxes of some different ammo this time and I was wondering if that might have been the problem, but after reading this thread I am going home tonight and inspect the release area and look for signs of any odd wear marks.

I am new at shooting and I know I have trouble with trigger control, a lot of low and left shots, so I did try a different grip at the last outing. I will try to get back to the range this week and pay close attention to my grip and see if I might be putting any pressure on the release that could cause the problem. I don't understand how bumping the release could cause the problem though. It seems to me if my thumb hit the release tab it would be applying an upward pressure and if anything that should make the slide latch more solidly. If my thumb got on top of the release tab wouldn't it be likely that I would be pinched?
 

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Watch that thumb! I never have a problem with the slide locking open on my M&P's but when I shoot other pistols (XDM, sigs and a few other) the slide never stays locked open on the last round because of my weak hand thumb. Because of the position of the slide release my weak hand thumb rides right on it and puts just enough pressure to make it not engage. So try adjusting your grip, and maybe try firing a few other pistols manufactured by different company's and see if you have the same problem!
 

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Well, I think my slide not locking was caused by me. I either saw, read, or was told, don't remember which, that I should grip my pistol a little higher up on the frame with my left hand to help control the recoil. I did some comparison to my original grip and my new grip and I do believe the heel of my left hand was riding on the release tab when using the new grip. I hope to get back to the range tomorrow night and do some more some more testing. This forum is filled with great information and great people. Thanks for giving me some insight on my problem. Now I just have to work on that trigger control.
 

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Your grip is likely touching the slide lock just enough to keep it from engaging on the last round. Very common for people to do. As for the auto forwarding, change the angle your holding the gun slightly when inserting the mag and the issue will go away.


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Oooh! I have never posted in an 8-year old thread before. This is kinda cool!
 
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