New (Used) MP40c Fail to Feed issues

Folks, Just got a used MP 40c yesterday, love the gun.
Love the ergos, when it feeds love the aim, etc.

I'm sure there are thousands upon thousands of owners who've never had a single failure. With my month old SD40VE, I'm with you. over 1000 rounds, not a single failure of any kind.
So, without sounding like a jerk, I'm not looking for a "I shot 10K rounds without issues" personal statements. I've read a TON of them on here. As said...I'm with you.

This 40c, not the case. Using reman ammo, 180 gr FMJ.
These are the same rounds I've show through my SD, I'm 99.99999% sure it's not the ammo. It's a well known and respected re loader.

I have both factory mags, one with the groove/extension, one with the flat plate. It didn't matter which mag I used, it didn't matter if I put in 5, 6, 7, ...or 10 rounds. So I'm ruling the mags out.

Out of about 90 rounds I put down range, about 20% failure to feed.
I'd rack the slide, clear the gun, and half of those failures would cause another failure. Rack again...and it would chamber the round but that last 1/4 to 1/2 inch is was "slow"...like sort of hanging. I should add, last night, field strip, complete clean and proper lube.

My first thoughts are polish the feed ramp. But I bought this gun used. It looks to be in very, very good condition. But I'd think that it was broken in enough where FTFeed would not be an issue.

Guide rod looks fine (Can't say I've ever heard of a steel/metal rod breaking, but...hey, I guess anything can happen).

Other than polishing the ramp, is there anything else I can look for.
This gun does NOT have an external safety, but it DOES have the Mag safety. Will not fire without the mag in.

Guys and gals, not looking to drag SW through the mud, not trolling, etc. I LOVE my SD40VE, so much I bought my girl the SD9VE two weeks ago. Both guns, flawless. I wanted a compact to carry...and I intend to fix this gun and carry it.
But until I can put a few hundred down range without a failure, well...you see where I'm going with that.
I look forward to your help and advice. Thank you!!

or change the recoil spring.

I bought a used 40C several weeks ago myself. Only had one range trip so far, but the pistol ran flawlessly with a variety of FMJ and HP factory and handloaded ammo in weights of 135, 155, 165, and 180 grains.

Before that range trip, I thoroughly cleaned and lubed the gun. Did you have an opportunity to give the gun a good cleaning/lubing before shooting it? If not, it is possible that the gun has a bit of crud in the wrong place, or that whatever lube is in the gun may have congealed a bit. I know I've had that happen to me before when I took a "new" used gun to the range without cleaning it first.

I will say that I am very impressed with the 40C, particularly with how well it handled the 40 cal recoil. It was also far more accurate than I expected it to be.

Saudade said:

or change the recoil spring.

Click to expand...

I gotta admit, it felt pretty darn strong and snappy, even in comparison to my month old SD.

Big Bore..
Field stripped and cleaned it last night.
I'd say it probably had a few rounds through it. It wasn't white glove inspection clean, but it was not horrible by any means. On par with my other gun after 100 or so rounds.
Cleaned up nice. I'm a fan of the Tetra products.

It did sit in my car in 20 degree weather while I ran errands, etc. Sat in my car for about 2-3 hours before I shot it.
However, I'd be disappointed if I couldn't feed the weapon in those temps.

Hmm... almost sounds like you might have gotten someone else's problem?? Anyway, even though you aren't the original purchaser, perhaps a call to C.S. might supply some ideas? Your original post sounded like you tried almost everything I would have, with the exception of trying different ammo. I know you said you are 99.99+% sure that's not the cause, but using some different factory ammo would make it 100%. I hope you can cure your issue and then enjoy a quality pistol.

Thanks Line..
I thought the same thing. I have some brand new I can throw down range to check. Hate to shoot my HD/SD ammo, but they're also a different grain (165 Hydra Shoks)
I can throw a box down range to rule out ammo. (I'd hate to think this gun can't eat anything I feed it...My "Value Edition" eats it all and begs for more..lol)

I'm beginning to feel the gun store knew and sold it for so cheap...and I got someone else's problem as well. I'm going to try new ammo, polishing up the feed ramp...and I'm shooting it where I bought it this weekend. If I still have issues...I'll just send it to SW and let them fix it.

No way to know what's been done with a used pistol. People can't seem to resist changing, modifying, trying to "improve" factory guns, etc.

Easy thing to try is to use FACTORY ammo in the gun, made by one of the major American ammo companies. FWIW, just because a full-size .40 may tolerate some reman ammo, that doesn't mean another of the same model FS gun might ... or that a compact version of another model might run with it. It can also depend on the brand of bullet used for the ammo, too, as wider/fatter ogives and noses may not clear the slide stop lever's tab during feeding.

I'd also start with fresh recoil and mag springs, just to put the new-to-you gun back to new-from-box spring rates. It could be something as simple as an out-of-spec recoil spring assembly (nut on front), or an earlier set of mag springs that have been damaged, tweaked or weakened.

The .40 followers have gone through some revisions. Might just be an older set of followers (although I've had fine service from both the 2nd & 3rd .40 followers in my 40c).

M&P .40 followers, oldest to newest (left to right, as looking at image):



Newest on top (look at supporting leg length difference):


S&W will probably send you new followers for free if you have older ones, and maybe even new springs (if they're in-stock).

If none of that works?

Send the gun to S&W.

The original slide stop lever spring in the compact was the light blue wire spring, and it was eventually replaced with a heavier tensioned yellow wire spring. The older spring could sometimes, in some guns, using some ammo, result in the slide stop lever lifting high enough during recoil/cycling to hang up on the corner of the slide's notch, stopping the slide, or slowing it as it returned forward (as the slide fell off the "hang up").

Now some "parts flutter" during cycling is normal and expected, but too much may cause an occasional problem. In other words, some slide stop lever bounce during the slide's run back and forth is to be expected, but the wire spring is supposed to keep the upward bounce from resulting in a locked back slide (or almost locked back, with the lever's inside tab hanging on the corner of the slide's notch).

My own '10 production 40c had this problem, BTW.

If you have the current yellow wire spring in the slide stop? Have the gun inspected by S&W. Could be a barrel issue, which the factory could either resolve with an adjustment, or they might take the easier/faster course and simply replace it.

Just some thoughts.

Fastbolt, excellent, excellent info and help. Thank you very much.
I did notice the recoil spring is yellow. I thought about asking, so glad you brought that up.
I will look at the mags when I get out of work and home in a bit. I'm fairly certain I have the newest, as I recall they have the .40 stamp on them that I don't see on the other two. However, I will look.
I would be disappointed if I couldn't target practice with the ammo I've been using. However, I have a box of hydra shoks I'm bringing to the range with me this weekend. New, never reloaded, etc.

I do plan on polishing up the feed ramp, I honestly feel that could possibly be the problem.
If not, I'm going to have to bit the bullet...pardon the pun, and send it to SW. I am not the original owner, I did buy it from a LGS.
I've been told by an old friend as well as a member on here, SW has the best warranty and coverage there is. If I get charged for peace of mind/reliability, so be it. If they take care of it on the house, great as well.
I will be sure to tell them I've literally purchased 3 of their guns in the last month, two brand new and this one used... Brand loyalty sometimes earns points....

Thanks for all the excellent pics and help fastbolt.

dajogejr said:

I did notice the recoil spring is yellow.

Click to expand...

The current recoil spring should have yellow paint at one end.

However, I was talking about the thin wire spring located on the inside of the slide stop lever assembly. It's located up front of the lever assembly, running up under the left side of the locking block, and tensions the slide stop lever. It's either painted light blue or yellow on the 40c, with the newest guns having the yellow wire. (The lever assembly with the yellow wire spring was available as a "repair" part for some 40c's even before the latest revision of the assembly to also incorporate angled bend or welded spacer.)

The slide stop lever wire spring has gone through some revisions since the guns were released. The original wire was unpainted, then the red & blue springs were released (depended on caliber), then the yellow spring (first developed for the .357 guns, I was told, but selectively used in some 40c's), and now the current assembly is going to have the yellow wire for all calibers ... until such time as this changes, of course.

1st thing is to try factory ammo. If that solves the problem, don't use reloads. Never mind that they work in another gun. My M&P40c book says to NOT use reloads, so I never do, on any gun. GARY

N4KVE said:

1st thing is to try factory ammo. If that solves the problem, don't use reloads. Never mind that they work in another gun. My M&P40c book says to NOT use reloads, so I never do, on any gun. GARY

Click to expand...

This could qualify as a good example of an understatement.

Of all the ammo-related problems I've seen stop courses-of-fire over the years, so someone could resolve some stoppage, the use of handloads, reloads and remanufactured ammo runs at the top of the list.

We still see factory ammo problems every now and again, but significantly less often than when folks bring their handloads (or their friends handloads, or some gun-show reman ammo) to a range session, and over a much larger sampling of factory ammo.

Unless it's something made by my brother (who is even more precise and detail-oriented than I was when I was an avid reloader), or left over from when I was reloading with my dad, I won't shoot reloads or reman ammo anymore. Not in my guns.

OK...it does have the yellow wire inside as well.
I do have the latest/newest mag follower.
So...here's the problem IMO.
I took it down to clean it...and forgive me for not knowing the proper vocabulary for the part. But you can clearly see where the casing is rubbing. It was like that when I bought the gun and cleaned it before I first used it today (cleaned last night). I'm 100% certain the rubbing is what is causing it to fail to feed. However, I will buy a brand new box of ammo from the range just to eliminate any ammo related possible failures.
My SD manual also says not to use hand loaded or reloaded ammo that has not been ballistic checked, etc.

The language in both manuals as far as ammo is dead on the same.

Guys, I'll buy new ammo and try it. It's 100% clear the LGS I bought it off of had the same exact problem...and put it for sale anyways (I'm sure they test fired with reman ammo that they sell as well).

Here's some pictures of the underneath of the slide.
I put between 80 and 90 down range today, FYI.

Is the ejector bent? Last pic looks like the ejector is not seated correctly like it should be


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In addition to what Fastbolt has stated,for grins tear the mags down and clean them up real good if you haven't already.Had a similar problem with a brand new 40c a few years ago and dirty mags(yes brand new from the factory)was the problem.Good luck.

normal. those markings are from where the next round in the mag rides on the slide till the slide comes back and the round is then pushed up into the chamber where the round after that will ride in the same spot.

OK...not used to seeing that on my SD erick, thanks.
So, I'll try new ammo and I'll also disassemble the mags and clean 'em real good.

Bio...here's some better pics from a better camera.

I have a brand new 9mm CORE and that's how my slide looked after a 50 rounds.

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Possibly an extractor issue?

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Ah. Well best we can do is try diff ammo on saturday at cqt and see if that makes any difference. Try walmart in roseville they might have a 100 pack of winchester white box. I think they are $36.97 which is not bad for factory ammo


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I was also thinking maybe an extractor issue. Have you ever installed a apex kit? Its similar to mp40 as it is sd. Maybe pop the ejector and internals out and clean any crud in there. My sd had some wicked buildup when i finally installed the apex spring kit. Cleaned it all out. Its a little more in depth than a simple field strip n clean


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