Problem with M&P 10mm + Customer Service Nightmare

[oseaghin]

10 Round 45 ACP Unmodified
To my surprise this magazine cycled fairly reliably too. No mag drops, slow firing it seemed fairly reliable. With rapid firing the issues started showing up where the rounds would get stuck in the roof of the chamber. Not a big surprise with the factory feed lip spacing.

Tried the same 10 Round 45 ACP Unmodified as well, similar results (1 nose-up FTF out of 8 rounds Underwood 200gr and 7 SB JHP 180gr).

Extended 14rd 45 ACP Mag MODIFIED
The modified 14 round 45 ACP magazine (extended) worn in a little and now seems to fit 20 rounds of 10mm! It cycled light 10mm loads to heavier Underwood JHP and DoubleTap Hardcast with 99% reliability*! No mag drops, perfect feeding and cycling even with rapid firing.

Tried modifying the 10 Round 45 ACP in the same way you described in a different post. Used a hand seamer and annealed with a butane burner.
NOTE: MAPP burner would probably do a better job.
On average, the 10mm mag lips are 9.65-9.80 mm apart, and 45ACP mag lips are 10.25-10.40 mm apart. I was able to bend the 45ACP lips to 9.61-9.78 mm, and after I fired 116 rounds of 8 different types, the opening measured 9.54-9.80.

Result is a smashing success. No malfunctions whatsoever. Curiously, I can now shoot 40SW rounds as well (I elaborated in an earlier post).

After wearing in the magazine I was able to fit 15 rounds but after I did the feed lip mod on this mag it went back to 14 rounds max sadly.

Yes, it's 14 rounds. The capacity could definitely be increased if we had control over the channeling ribs' length. They don't need to be that long.
Alternatively, we could try 3D printing base plates. I don't have a 3D printer anymore, sadly, but it's def another project to tackle. Sigh. Thanks, S&W.

I already modded this mag and it should be good to go like the 20 rounder. Biggest annoyance is not having accurate round count peep holes.

My modded 45ACP mag is also not falling out freely when loaded to the brim (14 rounds of 10mm). Again, a different baseplate will definitely help.

Factory 10mm Mag Update
I fired a good 15 rounds of DoubleTap 200gr hard cast rounds and didn't have a single issue, no mag drop no failures to feed. The 24lb spring AND bending the mag catch/release spring (which increases mag release spring tension) is still working well too.

As mentioned in an earlier post, I tried going back to the stock setup, and could no longer reproduce magazine drops.
I'd be very curious to see if you get the same result.
NOTE: this does not mean that there's no problem. The problems with the 10mm mag design are very much present:

1. Short channeling ribs.
2. Short feed lips.

For some reason, the ultimate manifestation (mag drop) seems to be affected by another, yet unknown factor.

CONCLUSIONS:
I would not trust the stock 10mm magazine.
I do trust the 45ACP magazine I modified.

 

[Farmer17]

So you've had a nightmare with a gun and with Smith and Wesson customer service for well over a year and 360 posts. I've owned an M&P 4inch 10 mm for about 5 months and it has been perfect in about every way, great accuracy, trigger, ergos, and perfectly reliable. Smith brought them out too early with not enough testing and fine tuning but most people I talk to who have recently bought them are not having any problems and like them. Every manufacturer turns out lemons occasionally including Glock, Rolex, and Lexus and I don't tolerate any guns that are not 100 percent relliable and I've owned over 100. Have you considered selling or trading your gun and getting a new one? Wasting all the Underwood ammo trying to fix the reliability can't be cheap.

 

[oseaghin]

I appreciate the feedback and the concern!

So you've had a nightmare with a gun and with Smith and Wesson customer service for well over a year and 360 posts.

I wasn't the person who started the thread. OP has identified 26 (!) people who have had this problem. I've meaningfully interacted with at least two others (so 4 total) who (1) had this problem, (2) were willing to let the world know, and (3) took steps to sorting it out.
OP was actually able to return the gun to S&W -- after a back-and-forth with the customer service and an open letter to the CEO.

Have you considered selling or trading your gun and getting a new one?

No. I cannot in good conscience sell a defective item to anyone.

Wasting all the Underwood ammo trying to fix the reliability can't be cheap.

Indeed it isn't cheap, but I do not regard it as wasteful. I'm a tinkerer, I'm learning a new skill, and showing a big middle finger (in a way) to a major gun manufacturer in the process. Turns out a couple of dudes on the internet can 100% figure out obscure design flaws of a new semiautomatic firearm, while the manufacturer could not and/or would not.
The issue started as a big disappointment, and now it's just a fun project and a great convo starter at a range.
Also I now know which manufacturer to avoid like a plague.

Smith brought them out too early with not enough testing and fine tuning but most people I talk to who have recently bought them are not having any problems and like them. Every manufacturer turns out lemons occasionally including Glock, Rolex, and Lexus and I don't tolerate any guns that are not 100 percent relliable and I've owned over 100.

The difference between an abstract lemon and this specific situation is that I know exactly what's wrong in this case. It's the magazine. I have inspected, out of curiosity newer magazines and newer MP 10mm guns -- mag design is identical.
Which leads me to another point...

I've owned an M&P 4inch 10 mm for about 5 months and it has been perfect in about every way, great accuracy, trigger, ergos, and perfectly reliable.

... is it though? As in, are you sure it is 100% reliable? As in, do you know for a fact that you do not have the same underlying problem which may or may not manifest at some point in the future?
The reason I am asking this question is because
(1) I had the problem of magazine dropping,
(2) I can no longer reproduce it, and
(3) the fundamental problem (bad magazine design) is STILL THERE.

There are two tests you can do (in all likelihood you already own the ammo for it) to find out if you have this problem. I bet you do have this problem, and I would be most grateful if you performed the test and shared the results.

Test #1:

1. Buy S&B 180gr JHP ammo.
2. Load the magazine with 15 rounds and insert into the gun.
3. Observe the back of the mag drop button on the right side of the frame. It will be raised by 1/16" or more.
   This is because the round #11 is flush with the mag catch window due to the channeling ribs being too short. In turn, the mag catch is resting on a bullet if the bullet is large/wide enough.
   
   

Test #2:

• Buy Underwood 220gr Hardcast (U220HC) ammo.
• Load the magazine with 15 rounds of any 10mm ammo, except make sure that round #11 is U220HC.
• Chamber a round (any ammo).
• Top off the magazine (any ammo).
• Fire a shot.
• Repeat steps (3)-(5) several times for a good measure.
  NOTE: the goal here is to keep the same round in the same spot #11 when the gun is fired.
• Observe that bullet in round #11 has deep scratches.
  Those scratches are made by the mag catch pressed against the bullet under the stress of the gun being fired.
  
  

 

[rosewood]

That there my friend is cause R&D. That is how you trouble shoot and find the solution to a problem.

It is also called teamwork. Took an entire internet Forum of gun nut/shade tree gunsmith to figure it out, but we hemmed it up.

Rosewood

 

[Farmer17]

Quote:

There are two tests you can do (in all likelihood you already own the ammo for it) to find out if you have this problem. I bet you do have this problem, and I would be most grateful if you performed the test and shared the results.

Test #1:

Buy S&B 180gr JHP ammo.

Load the magazine with 15 rounds and insert into the gun.

Observe the back of the mag drop button on the right side of the frame. It will be raised by 1/16" or more. This is because the round #11 is flush with the mag catch window due to the channeling ribs being too short. In turn, the mag catch is resting on a bullet if the bullet is large/wide enough.

Reply:

I don't have any Underwood or S&B ammo I have 5 boxes of Sig 180 grain FP ammo. That's about the cheapest ammo I can find in Oklahoma City and its about 43 bucks per box at Cabelas. I looked at both sides of the mag release and inserted a loaded 15 rd magazine and the mag release looked the same on both sides. Nothing protruded on the opposite side. I've had no unintended magazine drops and I tried to bounce the gun around and use all my strength to rip the loaded magazine from the gun but was unable. I will keep an eye on the mag catch when I buy some other ammo but I'm not really interested in buying the lower power ammo.

 

[oseaghin]

I don't have any Underwood or S&B ammo I have 5 boxes of Sig 180 grain FP ammo. That's about the cheapest ammo I can find in Oklahoma City and its about 43 bucks per box at Cabelas.

A-ha, and there in lies the issue.
I can't seem to find the "FP" ammo you're referring to. I assume, that's a typo, and you're referring to either FMJ or JHP V-Crown rounds.
However, it does not matter, as they both clearly look to be narrow at the tip.
Please refer to this picture that illustrates the differences between the types of ammo.
Wide-nose bullets MAY cause the mag drop issue.
Narrow-nose bullets definitely MAY NOT cause the issue.

I looked at both sides of the mag release and inserted a loaded 15 rd magazine and the mag release looked the same on both sides. Nothing protruded on the opposite side. I've had no unintended magazine drops

This makes perfect sense, and I deeply appreciate you conducting the test. If I were to refer to my previous post, this Sig ammo looks and thus behaves just like the S&B FMJ in the picture with the mag catch button.
NOTE: I would like to recapitulate that -- by far -- NOT ALL Hollow Points cause this issue, but quite likely NONE of the Full Metal Jacketed bullets cause this issue.

I tried to bounce the gun around and use all my strength to rip the loaded magazine from the gun but was unable.

That is appreciated, but unnecessary -- especially since you've established that the mag catch does not contact the bullets. The micro-stress produced by the shot quite likely cannot be replicated by macro-efforts, but it's good to test anyways.

I will keep an eye on the mag catch when I buy some other ammo but I'm not really interested in buying the lower power ammo.

S&B is a very popular brand of target ammo, so it might be available in smaller stores near you.
I believe, Underwood can only be purchased online (well, in most locations).
If you do want high power stuff, you can't go wrong with Underwood. Their 220gr hardcast bullets are flying at true (within 50 fps) 1200 fps, which results in ~700 ft-lbs of energy.
Of note, they also manufacture quite a few different types of 10mm ammo aimed at self-defense with bullets ranging from 100 (1800 fps) to 200 grains (1250 fps).
NOTE: only Underwood rounds with hardcast bullets may produce the mag drop issue and thus only those are suitable for testing this issue.

 

[Farmer17]

I’ve heard a lot of guns will have trouble with the 220 grain Underwood ammo. When Glock brought out their generation five 10mm several of those guns had issues. Glock is pretty fast at getting the bugs out of a new design, Smith and Wesson sometimes not as fast. I’m pretty happy with the Sig 180s at 1250 to 1260 fps out of a 4 inch barrel, 28 oz gun that shoots to point of aim and I don’t have to fiddle with the sights. The 200 grain Underwood is about the same speed with only 20 grains more of bullet weight and I’m not sure if that would make a difference on anything I would shoot and it’s a heck of a lot more expensive so I wouldn’t be practicing as much.

 

[oseaghin]

I’ve heard a lot of guns will have trouble with the 220 grain Underwood ammo. When Glock brought out their generation five 10mm several of those guns had issues. Glock is pretty fast at getting the bugs out of a new design, Smith and Wesson sometimes not as fast. I’m pretty happy with the Sig 180s at 1250 to 1260 fps out of a 4 inch barrel, 28 oz gun that shoots to point of aim and I don’t have to fiddle with the sights. The 200 grain Underwood is about the same speed with only 20 grains more of bullet weight and I’m not sure if that would make a difference on anything I would shoot and it’s a heck of a lot more expensive so I wouldn’t be practicing as much.

Respectfully, you're missing the point of this thread and the magnitude of this issue.
Regarding your specific application and approach, you should have a problem-free experience.

 

[vram01k]

I keep on forgetting to check this thread, but I also have another recoil spring setup brewing so was hoping to test it out before I checked back .

Tried modifying the 10 Round 45 ACP in the same way you described in a different post. Used a hand seamer and annealed with a butane burner.
NOTE: MAPP burner would probably do a better job.
On average, the 10mm mag lips are 9.65-9.80 mm apart, and 45ACP mag lips are 10.25-10.40 mm apart. I was able to bend the 45ACP lips to 9.61-9.78 mm, and after I fired 116 rounds of 8 different types, the opening measured 9.54-9.80.

Result is a smashing success. No malfunctions whatsoever. Curiously, I can now shoot 40SW rounds as well (I elaborated in an earlier post).

Very nice! That's similar to what I was seeing/measuring too. I personally didn't want to apply any heat to the magazine because I didn't want to ruin the heat-treat knowing that I can't re-heat treat at home easily. I need to grind a slit into a screwdriver and bend them out soon.

As mentioned in an earlier post, I tried going back to the stock setup, and could no longer reproduce magazine drops.
I'd be very curious to see if you get the same result.

I had the same thought too when I installed the mag release to lefty (which should have weaker tension) and returning it back to righty. A couple mags were fine but then I would start getting random mag drops again or tip-up failures.

Maybe there is a break in period that is helping, but I can't think of a logical explanation on why breaking in would help. What does make sense is how hot/cold the frame is, I can see hotter frame being more flexible which would result in different characteristics then when it's cold and stiff.

I have also discovered another problem with the 10mm magazine: feed lips are too short.

1. A number of people reported FTFs with various rounds, including typical range ammo.
2. Curiously, I personally experienced multiple FTFs with the 40SW. Yes, I'm aware that the gun is not designed for it, but that's besides the point, as in general all 10mm guns shoot 40SW just fine.

I found out that with a 45ACP mag, my M&P 10mm eats the 40SW just fine. The 45ACP mag has much longer feed lips, which is thus the most likely reason for this performance discrepancy.
I need to write this all up properly...

Agreed, the feedlips being too short are causing some tip-up failures for me, especially when rapid firing 200gr hard casts (Underwood or Double Tap). Now I personally had no issues with .40sw out of my 10mm mags! Even with 24lb recoil spring.

My 45ACP mag is also prone to the same tip-up failures too, but that's because I haven't built that screwdriver tool to fully bend the feedlips together for 10mm application.

So you've had a nightmare with a gun and with Smith and Wesson customer service for well over a year and 360 posts. I've owned an M&P 4inch 10 mm for about 5 months and it has been perfect in about every way, great accuracy, trigger, ergos, and perfectly reliable. Smith brought them out too early with not enough testing and fine tuning but most people I talk to who have recently bought them are not having any problems and like them. Every manufacturer turns out lemons occasionally including Glock, Rolex, and Lexus and I don't tolerate any guns that are not 100 percent relliable and I've owned over 100. Have you considered selling or trading your gun and getting a new one? Wasting all the Underwood ammo trying to fix the reliability can't be cheap.

While I agree with your sentiment, this is my 4th 10mm handgun and I like it the most. I also waited a year to get the M&P10 hoping all the bugs were worked out... The amount of money that I had to pour into a Glock to safely (I've had a kaboom...) and accurately fire hardcast ammo is way more. After all that I still HATED the ergonomics. I've let others shoot my modified G20 and SW with hot ammo and people prefer the S&W, better ergonomics lead to better recoil control by the operator which leads to better accuracy.

Plus being Optics Ready is big deal too, glad I didn't waste money milling the G20 or G29 that I still have (for now?)

Speaking of which, M&P 10mm in 4" is basically the same size/footprint as the G29 but with 4-5 extra rounds. I also have had a lot of issues getting reliable feeding with the G29 and 15 round mags.

If Smith & Wesson can listen to us and just adjust their magazine dies, I think we are going to be golden.

I’ve heard a lot of guns will have trouble with the 220 grain Underwood ammo. When Glock brought out their generation five 10mm several of those guns had issues. Glock is pretty fast at getting the bugs out of a new design, Smith and Wesson sometimes not as fast. I’m pretty happy with the Sig 180s at 1250 to 1260 fps out of a 4 inch barrel, 28 oz gun that shoots to point of aim and I don’t have to fiddle with the sights. The 200 grain Underwood is about the same speed with only 20 grains more of bullet weight and I’m not sure if that would make a difference on anything I would shoot and it’s a heck of a lot more expensive so I wouldn’t be practicing as much.

With the slight modifications to the SW (24lb recoil spring and bending mag catch spring OR modded 45 ACP mag) I've had no issues with 220gr vs 200gr both did well. I personally carry the 200gr though since I have a 4" model and extra FPS is more important to me.