M&p .40 issue - need some help

[SPEEDGUNNER]

M&P .40 issue - need some help

Headed out for a much needed trip to the range today, wanted to run a few mags through my fullsize M&P .40. I had noticed last time I had it out that it would occasionally fail to cycle (round fires, slide comes back and ejects shell cleanly, then slide fails to come forward and strip fresh round into chamber) and I would have to just give the slide a tug to get it to unstick and go forward - almost like it was locked back on an empty mag. Well, you guessed it, same problem today. I am only using factory mags and factory ammo, a mix of Speer Lawman and American Eagle 165gr and Winchester 180gr Target/Range. Is it the ammo, is it the mags, is it the spring, what is it? Suggestions, thoughts, help?

 

[Grandma]

Hubby and I went to the range last weekend, with our M&P .40 FS and .40 compact, and we used both the exact same ammo as you- American Eagle 165 and Winchester 180, which we ran approximately 100 rounds of each through both guns and neither had any problems. Just an fyi as I am not an expert but since we used the same guns and same exact ammo figured I'd add my 2 cents.

 

[handgunner356]

For the slide to stick back it almost has to be engaging the slide stop. Two things to check, is the slide stop spring working. Remove the mag and the slide and see if when you lift the stop it has enough spring tension on it to where it pulls it back down. Are you sure your thumb is not hitting the slide stop lever under recoil? This seems to be a common problem with polymer pistols, sometimes it helps to have someone watch you closely as you shoot to see.

 

[Fastbolt]

I agree.

Not uncommon for the shooter to unintentionally hit the slide stop lever during recoil (and not be aware of it).

Sometimes an ammunition issue can be involved, such as a wide bullet design which may wiggle a bit sideways during recoil and bump the slide stop lever tab.

However, the slide stop lever spring might be weak, too.

The current spring used in the M&P 40 (and M&P 45) is painted light blue (under the powder fouling ). My notes from an armorer class show that there were a couple of earlier springs, with the current one at that time being a red one, which we were told was stronger than the previous one. The light blue one is a later revision, it seems. FWIW, revisions are fairly normal when it comes to such things.

If you have carefully eliminated the potential for a shooter-induced (thumb placement) unintentional activation of the slide stop lever, I'd call S&W and ask for a shipping label for the gun to be checked under warranty. I'd also write a brief letter concisely detailing the instances in which you had it occur, the ammunition used and why you feel your grip may not be the cause of the matter.

 

[SPEEDGUNNER]

OK, I have checked my hold and I cannot see how I can possibly be activating the slide stop. But, that doesn't mean that I am not inadvertently doing it while firing the pistol. I am going to try to head back out to the range tomorrow and bang out a few rounds AND try to be aware of my hold.

Now, to the slide stop spring. My slide stop spring is UNPAINTED. Looks to be bare metal. Pistol serial is MPA60XX. Is this spring the issue, does the pistol need to go back to S&W for the upgrade to blue or red or whatever the latest color is??

 

[Spotteddog]

Check closely, the protrusion into the mag area as Fastbolt suggested. Does the profile of those bullets, allow them to move forward in the mag tube during recoil? To test, take a half full magazine and strike it forward smartly against a padded surface, then reinsert it in the weapon with the action being held open on the stop. While raising it nearly into full engagement, see where the slide stop's tab is relative to the bullet's ogive.

 

[SAMPO]

I agree with the above posters, it sounds like it might be a mag problem, if not I would check your grip also. I had a similar issue with a semi-auto, shot one-handed, weak-handed and the problem went away...turns out that with my two handed grip I was riding the slide stop/release lever. I would half-load your mags and see if you can get a half mag without any issues as well. Good luck

 

[RON in PA]

You have a very early M&P 40, one of the first 10,000 made. I'd call S&W and discuss your problem. I'll bet that some revisions have been made over the last two years or so. They might want to work on your gun or may send you new parts.

My M&P 40 is also an early one and the only problem I have encountered was failure to feed the last round in the mag. This only occurred in the first 200 rounds, no malfunctions since.

 

[SPEEDGUNNER]

Gotta love it

I took a quick run back to the range today and ran a few mags through the pistol using a more "scientific method". OK, all I did was keep track of which ammo was in which mag, and I made certain that my hold was not engaging the slide stop. After 6 mags, and shooting with both my right and left hands, I experienced multiple stoppages due the the slide locking back, and it was not because I touched the slide stop with my thumb or hand. You can see where the top round in the mag is edging forward, and there is the chance that it is catching the little tab on the slide stop. Something is definitely engaging it, and that isn't a big issue at the range, but would be a REAL big issue in competition or on the street.

Called S&W, explained the issue, they are sending me a call tag. Gotta love it.

Thanks for everyone for their suggestions, it pointed me in the right direction to try and determine the problem. I appreciate the input.

 

[shawn mccarver]

Sounds like the slide is locking back even though there are still rounds in the magazine. This can be either: (1) operator error or (2) a problem with the slide stop protruding into the top of the magazine enough to be hit by the ogive of the bullet next up in the magazine. The former needs a different grip and the latter needs a trip to the factory.

Test for problem one by taking yourself out of the equation. If it still locks back you have problem two and a trip back to the factory with a thorough description of the findings is required.

 

[NateDog]

Could it be the feed ramp needs polishing?

 

[tension]

Fs .40

I have the same problem occasionally. About once every 3 or 4 magazines. I look forward to seeing if someone has a solution. I have a M&P 9mm compact and this FS .40. I really like both guns.

 

[49gmc]

i have the same problem. Otherwise I really like the gun. I'm almost decided to sell it becaused of this.

 

[NateDog]

You are having the same Issues I am currently having.. It is caused by Limp wristing... There is nothing wrong with the gun. The problem is you.. I thought my gun was messed up also until a Fire Arms Instructor told me I was limp wristing the gun. I told him he was crazy and he took the gun from me and shot 4 magazines through it without one single malfunction. Soon as I tried to shoot the gun it started malfunctioning again..

 

[pberry]

I have the M&P40c. It was doing something similar last year. On round 7 through 9 the round would catch on the front of the magazine. The bullet would ride over the magazine lip and the front of the brass would catch. I use a dremel tool to taper the front of the magazines and then polish them at the spot where the round slides over. After the modification the problem went away. It sounds like the same problem you are having. Good luck with it.
Phil

 

[SPEEDGUNNER]

Follow up

Here is the follow up to my issue discussed above. I boxed up both of my M&P .40's and returned them to S&W on Friday June 19th. I went on vacation, returning the 5th of July. FedEx came up the driveway on Friday July 10th, both pistols had the slide stops replaced.
A trip to the range this past week confirmed that the problem was indeed fixed.

Thank you to all who pitched in with suggestions as well as a huge THANK YOU to the folks at Smith and Wesson.

 

[strangelittleman]

Here is the follow up to my issue discussed above. I boxed up both of my M&P .40's and returned them to S&W on Friday June 19th. I went on vacation, returning the 5th of July. FedEx came up the driveway on Friday July 10th, both pistols had the slide stops replaced.
A trip to the range this past week confirmed that the problem was indeed fixed.

Thank you to all who pitched in with suggestions as well as a huge THANK YOU to the folks at Smith and Wesson.

I'm glad to hear your problem is solved, I'm new here, otherwise I'd have chimed in about my M&P40 service pistol doing the same thing, even when loading a mag from slide lock at the clearing barrel, it wouldn't go forward....
The culprit was that we are issued some of the first M&P40s that left the factory, so I had one of the weaker slide catch springs...No problem, our armourer just replaced it with the newer slide stop assembly w/ the "humped" stop & blue spring and the pistol has been good to go ever since!

 

[TSQUARED]

Speedgunner,
Has a person who regularly shoots 40 S&W out of a plasric gun used your M&P and experienced the same results? The reason I ask is because the recoil of the 40 S&W in a Glock or S&W M&P is sharp and limp wristing would lead to the problems you expereinced.

 

[Littledragon777]

My 945 shoots 5 shot groups around 2.75" at 25 yards with factory loads. With handloads I have managed to get that to 1.75" using Tite Group and 185 grain bullets. I normally shoot TiteGroup with 230 fmj bullets and that runs from 2.75 to almost 3 inches at 25 yards. Not the best accuracy in the world with the 230 grain loads but if I can keep them under 3 inches with these old eyes I can live with shooting the 230 grain loads.