40c Firing Issue

[Coastie762]

Out of curiousity, what do the fired cases look like? Is there any damage to the case mouths on any of them?

If the slide is not travelling fully to the rear due to limp wristing, you may see the case mouths damaged where they contact the front/top of the ejection port instead of being thrown clear. There will also be brass marks on the slide where the cases are hitting.

Also, as the slide did not move fully rearward, as it starts forward the new round may not be fully positioned for feeding, and catch on the bottom edge of the feed ramp.

This condition can be compounded with a full magazine and drag caused by the pressure from the magazine spring as noted above.

Don't ask me how I may know this...

 

[mewisemajic]

I just replaced the recoil spring on my M&P9 FS and I noticed that with a new mag loaded to 17 it will drag the top round in the mag. I did this with a snap cap in the chamber and dummy rounds in the mag. I didn't see it carry over to live fire though.

If it's only happening with the 10rd mag I would say it was a mag problem, not a problem with the 40c itself.

 

[EXERCISINGTHE2ND]

I had over 500 rounds before it started.

Seems to happen after 50 rounds and gun is warmed-up.

Did notice brass marks on the bottom of the slide on the ejection side.

Thought about "limp wrist" and ensured help tight - still felt.

Feels as if the slide comes back, but returns with a "jerking" motion as if 1) something is preventing the slides return and 2) there is not enough spring pressure to return the slide while picking up the next shell because the slide did not go all the way back.

I haven't been to the range since I started this thread so that I could get really good advice as to what to do at my next NRA Range visit.

Thanks all

 

[Mikey217]

I'm having the same issue with my 1 month old 40c. It seemed to happen quite a lot at the range yesterday. I fired 150 rds of American Eagle 180gr through it. Once or twice, it even paused for 4 -5 seconds before travelling the last few cm into battery. It was really weird.

Next time I go to the range, I'm going to do some more thorough testing by marking the mags, trying different ammo, ensuring a good grip, etc. I have 6 10-rd mags that I use, but I only load them up with 5 rds at a time while I'm at the range.

Another oddity yesterday was that almost all of my spent brass was going a good 7-8 feet to my right. Previously, they usually only travel about 3 -4 feet. Following the guidelines in a previous post, I'm going to examine the brass closely this weekend, as well as the feed ramp/ejection port, looking for excessive marks or damage.

I'll update after my next range trip.

 

[xzhync]

I'm having the same issue with my 1 month old 40c. It seemed to happen quite a lot at the range yesterday. I fired 150 rds of American Eagle 180gr through it. Once or twice, it even paused for 4 -5 seconds before travelling the last few cm into battery. It was really weird.

Next time I go to the range, I'm going to do some more thorough testing by marking the mags, trying different ammo, ensuring a good grip, etc. I have 6 10-rd mags that I use, but I only load them up with 5 rds at a time while I'm at the range.

Another oddity yesterday was that almost all of my spent brass was going a good 7-8 feet to my right. Previously, they usually only travel about 3 -4 feet. Following the guidelines in a previous post, I'm going to examine the brass closely this weekend, as well as the feed ramp/ejection port, looking for excessive marks or damage.

I'll update after my next range trip.

For me the problem only occurs with the 10 round mag and is most pronounced when there are 5 or less rounds in the mag. Seems like the mag spring exerts significantly more upward force at that point until the mag is empty. Try pushing rounds out of the mag with your index finger. You will feel that you have to push much harder from 5 rounds down to zero

 

[Coastie762]

I apologize in advance for the length of this post. Hopefully it will make a bit of sense.

I've spent a bit of time at the range this weekend with both my 40 FS and a new 40C. Based on my testing, I now think the hesitation that I've experienced and has also been reported above may be due to the slide stop moving (bouncing) under the forces of recoil and trying to catch in the notch in the slide. This causes the hesitation felt as the slide goes forward. Sometimes it just briefly catches the notch, sometimes it will cause the slide to lock back as if the mag was empty.

The condition was only noted when shooting full power loads and as the mag was partly empty. The partly empty mag provides less pressure on the underside of the slide and a faster slide velocity.

The first time out with the 40C yesterday, the slide locked back early several times when firing full power 180 grain factory loads and heavy handloads. Especially when, as noted above, there were 5 or fewer rounds left in the mag. Light handloads and Privi factory loads (very mild!) ran without problems. BTW these light loads also cycled properly in my 40 FS with a 20-lb ISMI spring installed.

There were no marks on the slide stop to indicate that it was being prematurely actuated by a round in the magazine.

I loaded up some "medium-heavy" 180 handloads and tried them this morning. These loads did not lock the slide early, but I did get the "jerky" slide return, as seen before, after the mag was partially emptied. This was also noted, to a lesser extent with the FS.

If anyone having this problem has access to some lighter loads or handloads, try some and see if your pistol runs smoothly.

The ideal solution would be a heavier slide stop spring, but I am not sure if one is currently available. In the meantime, I'm going to have to buy a spare slide stop assembly to play with and see if I'm on the right track.

 

[xzhync]

I apologize in advance for the length of this post. Hopefully it will make a bit of sense.

I've spent a bit of time at the range this weekend with both my 40 FS and a new 40C. Based on my testing, I now think the hesitation that I've experienced and has also been reported above may be due to the slide stop moving (bouncing) under the forces of recoil and trying to catch in the notch in the slide. This causes the hesitation felt as the slide goes forward. Sometimes it just briefly catches the notch, sometimes it will cause the slide to lock back as if the mag was empty.

The condition was only noted when shooting full power loads and as the mag was partly empty. The partly empty mag provides less pressure on the underside of the slide and a faster slide velocity.

The first time out with the 40C yesterday, the slide locked back early several times when firing full power 180 grain factory loads and heavy handloads. Especially when, as noted above, there were 5 or fewer rounds left in the mag. Light handloads and Privi factory loads (very mild!) ran without problems. BTW these light loads also cycled properly in my 40 FS with a 20-lb ISMI spring installed.

There were no marks on the slide stop to indicate that it was being prematurely actuated by a round in the magazine.

I loaded up some "medium-heavy" 180 handloads and tried them this morning. These loads did not lock the slide early, but I did get the "jerky" slide return, as seen before, after the mag was partially emptied. This was also noted, to a lesser extent with the FS.

If anyone having this problem has access to some lighter loads or handloads, try some and see if your pistol runs smoothly.

The ideal solution would be a heavier slide stop spring, but I am not sure if one is currently available. In the meantime, I'm going to have to buy a spare slide stop assembly to play with and see if I'm on the right track.

You may be on to something. I didn't think much of it, but I also have been experiencing occasional slide lock backs. I thought that was an unrelated problem. Definitely worth some further investigation.

 

[EXERCISINGTHE2ND]

So with the slide issue, I believe my 40c is MD compliant with the internal lock. Could this be any part of the issue and/or something else with the compliant weapons?

 

[Coastie762]

EXERCISINGTHE2ND, None of my M&Ps have the internal lock, so at least in my case they are a non-issue. I have not heard of any firing-related problems traced to the internal locks in the M&P series (unlike the revolver system).

I think the issue is more related to the "one size fits all" system in use for various parts of the M&P platform. Except for barrels and mags, pretty much every other part will interchange between the 9mm, .40 and .357 Sig, caliber pistols. Thats great for mass production; less so for tuning a pistol to different calibers of differing power levels. For example, the same strength recoil spring assembly is used for the above three calibers. Works, yes but probably not optimal.

Midway had slide stops in stock and I needed some other stuff anyway so I've got one on order. There are a few tweaks I want to try to confirm that the problem is actually related to the slide stop. I figured that if I screw it up, I still have the original one to reinstall.

 

[xzhync]

EXERCISINGTHE2ND, None of my M&Ps have the internal lock, so at least in my case they are a non-issue. I have not heard of any firing-related problems traced to the internal locks in the M&P series (unlike the revolver system).

I think the issue is more related to the "one size fits all" system in use for various parts of the M&P platform. Except for barrels and mags, pretty much every other part will interchange between the 9mm, .40 and .357 Sig, caliber pistols. Thats great for mass production; less so for tuning a pistol to different calibers of differing power levels. For example, the same strength recoil spring assembly is used for the above three calibers. Works, yes but probably not optimal.

Midway had slide stops in stock and I needed some other stuff anyway so I've got one on order. There are a few tweaks I want to try to confirm that the problem is actually related to the slide stop. I figured that if I screw it up, I still have the original one to reinstall.

The thing I find curious is if it turns out to be the slide stop then, in my case, why does the slide dragging issue only occur with the 10 round mag and not the 15 round mag?

Do you have both mag sizes? Does it happen with both or just one mag size?

Yesterday I measured the distance between the mag feed lips and found the 15 round mag was over 1/64 wider. I opened up the the feed lips on the 10 round mag and polished the surface. That seemed to make a difference when hand cycling rounds through the gun. I haven't been to the range with this mod, but hope to this week.

I wonder if the spring on the slide lock can be adjusted (tightened)?

I would think that if it is the slide lock, by installing a new one, the problem would temporarily go away.

It is sad, but I think the folks on this thread will solve this problem far faster than Smith & Wesson. When I sent mine in for this problem they polished the feed ramp and replaced the extractor and spring. I am not a gunsmith and I can tell you that their fix is nowhere near the right solution. It really irritates me when they don't even make a reasonable attempt at fixing a problem.

Please let us know what happens with the new slide lock.

 

[turbo38gn]

The thing I find curious is if it turns out to be the slide stop then, in my case, why does the slide dragging issue only occur with the 10 round mag and not the 15 round mag?

Do you have both mag sizes? Does it happen with both or just one mag size?

Yesterday I measured the distance between the mag feed lips and found the 15 round mag was over 1/64 wider. I opened up the the feed lips on the 10 round mag and polished the surface. That seemed to make a difference when hand cycling rounds through the gun. I haven't been to the range with this mod, but hope to this week.

I wonder if the spring on the slide lock can be adjusted (tightened)?

I would think that if it is the slide lock, by installing a new one, the problem would temporarily go away.

It is sad, but I think the folks on this thread will solve this problem far faster than Smith & Wesson. When I sent mine in for this problem they polished the feed ramp and replaced the extractor and spring. I am not a gunsmith and I can tell you that their fix is nowhere near the right solution. It really irritates me when they don't even make a reasonable attempt at fixing a problem.

Please let us know what happens with the new slide lock.

Maybe they didn't experience the same problem as you. How do you think they could fix something that isn't happening. I am a mechanic. I have plenty of customers come in with a complaint. I roAD TEST THE CAR AND IT DOESN'T EXHIBIT THE SYMPTOM, HOW DO I FIX IT? I don't doubt the customer.... but it happens. So maybe if you contact them again and really explain your concern in a respectful and sincere manner, you may get more help. Complaining over and over on a BB is not gonna fix it, nor does it give S&W a fair shake. I cannot imagine a technician experiencing a problem with your gun and ignoring it, that just does not make sense.

 

[Mikey217]

So maybe if you contact them again and really explain your concern in a respectful and sincere manner, you may get more help. Complaining over and over on a BB is not gonna fix it, or does it give S&W a fair shake. I cannot imagine a technician experiencing a problem with your gun and ignoring it, that just does not make sense.

I would cut xzhync some slack. I can see both sides of the argument. S&W apparently only worked on his gun for approx 4 days. You'd think that if they couldn't find anything wrong they'd give him a call and ask for more information. Isn't that what you do as a mechanic? And on the other hand, yes it can be extremely difficult to troubleshoot something that is intermittent. But, I do think that if they had contacted him and asked for detail similar to what's posted in this thread, maybe they would have had better luck resolving the issue.

Just a thought...

 

[Mikey217]

I think the issue is more related to the "one size fits all" system in use for various parts of the M&P platform. Except for barrels and mags, pretty much every other part will interchange between the 9mm, .40 and .357 Sig, caliber pistols. Thats great for mass production; less so for tuning a pistol to different calibers of differing power levels. For example, the same strength recoil spring assembly is used for the above three calibers. Works, yes but probably not optimal.

Yes, I too find this disconcerting. My last pistol was a Glock G19. I load my own ammo and had about 5 different recoil springs I used for different loads. I try to do the same with the M&P 40c... no can do. The ONLY recoil spring available is the one that comes with it, which is also used in the 9mm and .357, as you mentioned. I don't like it. Had I realized that before I purchased the M&P, I probably would have looked elsewhere.

On another note, you all have given me some really good information on how to tackle this weird slide issue. I'm out of factory ammo and plan on hand loading some this week. I'll make some sub-sonic loads and see if that makes the problem go away.

Thanks for all of your feedback!

Mike

 

[xzhync]

I would cut xzhync some slack. I can see both sides of the argument. S&W apparently only worked on his gun for approx 4 days. You'd think that if they couldn't find anything wrong they'd give him a call and ask for more information. Isn't that what you do as a mechanic? And on the other hand, yes it can be extremely difficult to troubleshoot something that is intermittent. But, I do think that if they had contacted him and asked for detail similar to what's posted in this thread, maybe they would have had better luck resolving the issue.

Just a thought...

When I sent my gun in I sent a very detailed letter explaining the issue. In the letter I told them that they absolutely needed to fire 4 or 5 mags to ensure that they experienced the problem. I wasn't there but I would be willing to bet the only rounds that were fired were fired after they polished the feed ramp and changed the extractor. I bet they only fired 4 or 5 rounds.

In the letter I provided my contact info in great deal and asked them to call me with any questions. They had my gun for almost 2 weeks, but it sat on the shelf for all, but part of a day. I know because I called several times.

I had several people at my local range fire the gun and each person said they felt it. If the technicians had fired it based on my request and fired it like people shoot at a range then I can't believe they didn't experience the issue.

I do believe this problem is tough to diagnose, but that doesn't mean they should make a silly attempt to fix it without calling me to discuss. As I said in a previous post it felt like they were just trying to get me to go away.

I admit I am venting. I am a bit frustrated. I would have expected a better effort out of them.

 

[Mikey217]

I hear ya, xzhync. It does sound like you did everything right. I'm getting pretty frustrated as well. I NEVER had these kind of odd issues with my Glock. This gun does feel better in my hand, though, than the Glock, so I'm willing to go through the motions to try to resolve this... for a bit longer.

I tell you, it's embarassing at the range when people ask, "What is that you're firing?" I proudly tell them it's a Smith & Wesson M&P 40c, then they see me having issues with the slide sticking. They're probably thinking, "He should have bought the XDS instead."

Thanks again for sharing your experience in detail with us.

Mike

 

[Coastie762]

The thing I find curious is if it turns out to be the slide stop then, in my case, why does the slide dragging issue only occur with the 10 round mag and not the 15 round mag?

Do you have both mag sizes? Does it happen with both or just one mag size?

Yesterday I measured the distance between the mag feed lips and found the 15 round mag was over 1/64 wider. I opened up the the feed lips on the 10 round mag and polished the surface. That seemed to make a difference when hand cycling rounds through the gun. I haven't been to the range with this mod, but hope to this week.

I wonder if the spring on the slide lock can be adjusted (tightened)?

I would think that if it is the slide lock, by installing a new one, the problem would temporarily go away.

It is sad, but I think the folks on this thread will solve this problem far faster than Smith & Wesson. When I sent mine in for this problem they polished the feed ramp and replaced the extractor and spring. I am not a gunsmith and I can tell you that their fix is nowhere near the right solution. It really irritates me when they don't even make a reasonable attempt at fixing a problem.

Please let us know what happens with the new slide lock.

The questions regarding why you only experience the problem with the smaller mag are good ones. It may be due to a difference on how the pistol recoils in your grip. The longer 15 rd mag gives you a better lever to counter the upward force of the recoil than the shorter 10 round mag.

As for myself, my chicken wrists probably add to my issues as I can replicate the issue on both my FS and C. The difference I see is that the FS does not lock back, just gets the occasional hesitation as the slide moves forward, depending on the load used.

I did shoot a 15 rd mag w/ X-grip in the compact, with full power loads I did get the slide hesitationas the mag approached empty but don't remember if it locked back early.

Anyone know how S&W tests their pistols returned for warranty work? Machine rest? Technician named Mongo?

 

[xzhync]

I disassembled the frame last night and attempted to adjust the spring tension on the slide stop. I will try and test it this week.

 

[mrk0830]

40c issues also!

Fired 40c today at range. Fired 102 rounds and slide hung up and went into battery and sometimes not. IMHO I believe I isolated the problem to only one of my three mags. I could not get the problem with the other two mags. I will comment this is by far the stiffest mag springs of all the double stacks I have ever owned. I honestly feel it is a mag issue. Like a dummy I meant to mark the bad mag but forgot. Next range trip is this thursday so I will post again and see what happens. My round count is 252. My m&p has performed so well and fits my hand so well and I shoot it as good as can be so basically I intend to resolve this issue whatever it takes. What I am saying is I am in this for the long hall. I will fix it or s&w will. Frustrated as it is my edc but we will see....

 

[xzhync]

I disassembled the frame last night and attempted to adjust the spring tension on the slide stop. I will try and test it this week.

Well, I went to the range today with my "fixes" and I am pleased to say that the slide drag appears to be gone. I am not sure if it was the work I did on the mag or the fact that I adjusted the spring tension on the slide stop lever...or both, but the gun is 100% better. I also brought a brand new 10 round mag with me which had never been used. With the new mag I felt some slide drag...but a little less than I was experiencing with the original 10 round mag. I measured the distance across the feed lips of the new mag and it was only a hair narrow compared to my 15 round mag which gives me no problems. I will try to adjust the new 10 round mag just like I did to the other one.

Anyway, it looks pretty good at this point.

By the way I used my 9mm barrel and 12 round 9mm mag today and the gun shot great, without a single issue. The gun almost makes a better 9mm than it does a 40 cal. I seem to be more accurate with it as a 9mm.

 

[mewisemajic]

IMHO I believe I isolated the problem to only one of my three mags. I could not get the problem with the other two mags. I will comment this is by far the stiffest mag springs of all the double stacks I have ever owned. I honestly feel it is a mag issue.

I have an M&P9 FS born in 2006, which is when I bought it The new mags and mag springs are completely different and much stiffer than the mags that came with it and the extras I bought back then. It's not that they got used a ton either. It set in the factory case for the vast majority of the time until this year. I have it fired more in September and October than I did in the first five years I owned it.

I hope you or S&W get your problem resolved.