M&P Shield .40 Blow Up

[Buttercup]

Here is some winchester I had sitting out. It is stamped winchester.

 

[N.P.E.S.]

This issue occurred a lot on early glocks. Some engineers believed it was due to an unsupported chamber and or loads with too much pressure. The vast majority of cases showed .40 caliber a doing it. .40s developed from the 10mm and are very high pressure. That case pictured looks like it fired without the round seated. In fact that is exactly what happened. When it's seated the case doesn't have anywhere to go. When not seated the pressure will find an easy way out and with no barrel support, it can go through the brass.

 

[41Magdude]

First off, to those who are concerned about the shield, there have been NO issues with the 9mms, all the kabooms are in the .40s. From everything I have seen so far, this is an issue with the chamber not supporting the case head. As mentioned before, this was a big issue for Glocks for quite some time. Also, I have noticed that this happens more often with reloaded ammo than commercially produced. It could be a double charge, or a weak case. If they are reloads and the "smily" ends up in the exact same place that it was before, Kaboom! Seems like all of the factory ammo issues come from Winchester white box ammo. So for the most part, this is an ammo problem, not a problem with the gun. I will say I have seen pictures of the shield's barrels and the chamber apparently varies in depth with some having a lot of the case exposed. This, IMHO, is a gun problem, but its a problem with all manufacturers and the .40 S&W. I understand that the pressures in the .40 and 9mm are similar, but apparently it is harder for the .40s to feed reliably since so many suffer from and unsupported chamber as compared to the 9mm. Also, you are trying to cram a larger caliber round into as small of a gun as possible and that alone creates engineering challenges when trying to reliably feed ammo AND support the case fully. I am a fan of the XDs and carry one in .45 often. They have since released a 9mm version that has been out for quite sometime. With the popularity of the .40 round, I often wonder if these issues are the reason why a .40 has not been released. Food for thought

 

[Offshell]

Have the PPS, nano, or CM/PM40 had similar issues? I know there's been reported kabooms in them before, but I'm curious if they are occurring at the same frequency as the Shield. They are both roughly in the same size category. Either way, my only 40 at the moment is a glock and if I added another it'd probably be an H&K. I'm perfectly happy with the Shield in 9mm.

 

[N.P.E.S.]

All 40s are at risk because of the pressures. A couple of factors that help increase the likelihood are weaker brass (reloads), an unsupported chamber (where there is unencompassed brass), gun not getting into battery, and firing (which leaves brass open, and makes a more resistant path for the projectile) and setback (chambering the same round over and over.) With the 40 pressures, setback is a very dangerous thing if it happens bad enough. The further into the casing the projectile gets pushed, the more the pressure multiplies. Almost all KBs (not all) are 40 caliber.

 

[41Magdude]

All 40s are at risk because of the pressures. A couple of factors that help increase the likelihood are weaker brass (reloads), an unsupported chamber (where there is unencompassed brass), gun not getting into battery, and firing (which leaves brass open, and makes a more resistant path for the projectile) and setback (chambering the same round over and over.) With the 40 pressures, setback is a very dangerous thing if it happens bad enough. The further into the casing the projectile gets pushed, the more the pressure multiplies. Almost all KBs (not all) are 40 caliber.

So are your thoughts that on commercial ammo, are the rounds not crimped enough? I understand that the round headspaces on the case mouth, but some crimping is needed to prevent setback

 

[N.P.E.S.]

So are your thoughts that on commercial ammo, are the rounds not crimped enough? I understand that the round headspaces on the case mouth, but some crimping is needed to prevent setback

That could be a reason, yes. I have absolutely seen setback occur. No question about it. The trick is to not chamber it more than a time or two, to be absolutely safe.

 

[Eugene 9mm]

Nope, not at all. The .40S&W has exactly the same pressure specs as the 9mm which is 35Kpsi maximum.

All 40s are at risk because of the pressures.

So what am I missing here? Is 40 S&W the same pressure as 9mm, or not?

Rastoff, I can see from your posts that you are knowledgeable, can you explain a bit more why the .40 is called a 'hot' round if it's not to do with high pressure? I see where you get the 35Kpsi, but my understanding is that the .40 S&W cartridge typically pushes the gas pressure inside the cartridge/barrel combination closer to that failure point, and that's why there are more accidents like the one we are discussing - there's a smaller margin or error.

I grabbed three boxes of ammo that show the muzzle velocity and energy:
Federal .45 230 grain: 890 fps, 405 ft-lbs
Winchester .40 165 grain: 1060 fps, 412 ft-lbs
Federal 9mm 115 grain: 1125 fps, 323 ft-lbs
and also:
Federal .22R 40 grain: 1240 fps, (ft-lbs not stated)

So how do you get a heavier bullet (165 vs 115) to travel faster without having higher pressure behind it?

Or, how do you impart more foot-pounds, i.e. energy, into a moving bullet, if not by applying more force to it, via higher pressure build up in the cartridge and barrel behind the bullet?

I know I'm missing something here, and I'd like to understand what it is. While the .40 has more ft-lbs than the .45, if I multiply muzzle velocity by grains to get grain feet/second, the .45 comes out at 204700 and the .40 174900 (9mm is 129375).

At this point my maths brain starts to complain and say I should go watch a movie where people fly several feet backwards when hit by a single bullet.

My Winchester .40 rounds are labelled W I N and 40 S&W. They are in a 100 round value pack bought at BiMart, and the box is labelled *WIN* pack.

 

[S&WForty]

Nobody took note of this posting? "It is clear the round fired outside the chamber. It looks like the case of the round is being trapped between the chamber and extractor."
Can we please discuss this guys?
Is this an "out of battery" firing? Something different?
The cause of this KaBoom?

Can Matt post a photo of the bad round from the side, so we can see it from another angle? How far from the rear of the casing did it rupture? Is this Unsupported Chamber or Firing Out of Battery?

All the talk about 9mm vs .40 pressure is interesting, but if this kaboom is due to firing "OOB," then I think that is where everyone's focus should be.

IIRC, they are not supposed to fire OOB.

 

[peterthefish]

Can Matt post a photo of the bad round from the side, so we can see it from another angle? How far from the rear of the casing did it rupture? Is this Unsupported Chamber or Firing Out of Battery?

All the talk about 9mm vs .40 pressure is interesting, but if this kaboom is due to firing "OOB," then I think that is where everyone's focus should be.

IIRC, they are not supposed to fire OOB.

I'd rather see a pic of the kaboomed round in the barrel. I had a case head separation in my FNP .45 (reload / bad brass) and the casing fits the chamber / feed ramp proving it was an in battery failure.

Re the .38 SPL ammo marked Winchester - I have .45 ACP marked the same, but the OP wasn't shooting 38 or 45. And current commercial WWB .40 is marked WIN.

There is no way this round was caught in front of the extractor and fired OOB as a result. The firing pin wouldn't have been able I set off the primer, and the primer would likely look quite a bit different as it would not be held firmly against the bolt when fired and so backed out.

Also, if it was in front of the extractor the gun would not be able to lock into battery even if it could somehow fire the round. If this fired OOB the case head would not be perpendicular to the case walls as it is here. It would have been pushed up and back as it would not be supported by the boltface while the walls of the cartridge stuck to the chamber.

Heavier projectiles can be moved fast with low pressure by using slower burning powders - reloading 101. The difference between Bullseye and Power Pistol. The .40 ACP is not at incredibly high pressure.

However, it is a larger / longer round and so the feed ramp (when used on a gun built for 9mm or a gun built to minimum size) tends to cut further into the chamber than you would see on a 9mm.

As a result, you get brass that bulges out more at the thicker (and harder, less flexible, and more brittle) case web. Multiple resizings and hot loads leads to case head separation where the thicker but more brittle brass has been overly work hardened by resizing.

Finally, I hear a lot about set back but I have never seen factory ammo in adequately crimped or suffer setback with multiple chamberings - certainly not the many hundredths needed to cause a KB. Case neck tension is plenty to hold a bullet in any auto pistol. WWB crimps their rounds a LOT (their .45 ACP almost looks roll crimped) which is overkill and probably has a more positive impact on consistent pressure / velocity than setback.

I think that answers everything.

/TLDR the reloads blew up the gun. Given the relatively minor extent of the damage, I'd say bad brass not double charge. Reloads are like underwear - you don't borrow them from a friend no matter how good they work for him, and if you do you might be sorry.

 

[uechikid]

Because there is nothing wrong with the firearm. Most if not all KABOOMs are due to overcharged commercial or hand loads done the same.
Ive shot both my shields alot with lots of different brands of ammo and sone home loads my father in law did. Not one FTE FTF or misfire
And no KABOOM. From what Ive seen heard and read S&W has pretty much said its bad ammo not a defective gun.

And the Ammo manufactures say there's nothing wrong with their ammo. Someone's not being straight. I say these KABOOMS are from a poorly supported chamber and S&W doesn't want to own up to it. Consult an attorney.

 

[emory]

There is no way that the primer is being struck while out of battery. The design of the gun makes this geometrically impossible.

It IS possible that a combination of weak brass and high pressure could exceed the yield strength of the case wall, and that the feed ramp intrusion into the chamber would allow case deformation in that area sufficient to produce strain in excess of the ultimate strain of the case material. This is the "hot load & poor chamber support" explanation and can likely be prevented by avoiding reloads and smoking hot boutique loads. This seems to be the most reasonable explanation for the kabooms discussed on this forum.

Another, less likely explanation, is that the slide is recoiling and unlocking the chamber before the internal pressure has adequately dropped. This condition would be exacerbated by the following things: Slower burning powder; Higher projectile mass; Longer barrel dwell time; Lower slide mass. It is worth noting that the shield has a very lightweight slide and all but one of the .40 shield kabooms discussed on this forum were with relatively heavy ammo. This condition could also be caused by a small misalignment of the steel lugs in the polymer frame causing the barrel to unlock prematurely. I doubt this is the cause, but it is worth considering.

The shape and location of the hole in the failed case, the 'Winchester' headstamp, and the position of the frame crack seem to indicate that this kaboom was due to a hot reload in weakened brass.

 

[tat2dchad]

what is this "clip" you speak of?

Smith & Wesson Pro Series Destroyed: Cata M&P stro…: Smith & Wesson M&P Pro Series Destroyed: Catastrophic Failure - YouTube

 

[FrankC2014]

Roger S&W.

Not sure that is why I brought it up in this thread. I aired on the side of caution and shelved it but my followers look similar to the OP's. It seems to be a feeding problem with mine at least, but not enough to keep it from full lock up (as of yet) There is an alignment issue somewhere. is it the mag? Angle of mag? Feed ramp? Don't know. Could it eventually cause an out of battery firing, maybe. Could it cause enough set back to increase pressure with that one whack to the round as it was entering the chamber? I don't know but I wasn't taking that chance until I could have Smith take a look at it. Out of the 400 rounds through mine, 100 were Federal 180's and the last 300 were WWB 165's. All purchased from walmart. I can guaranty that I am not introducing reloads as I don't reload so I could not have mixed and all my rounds were store fresh. Let me say that my 40 was flawless in it's function. Not a single issue until I noticed the dents on the projectiles and the chewed followers. When I found the issues with the 40 I purchased a Shield 9 as an interim CC and have about 450 rounds with no issues what so ever. Hope that answers your question Roger.

 

[Rastoff]

So what am I missing here? Is 40 S&W the same pressure as 9mm, or not?

You're not missing anything. The thought that the .40S&W has higher pressure is pure gun folklore. I used to believe it too until I did some actual research rather than just believe the fish stories told at the gun range.

Just so I'm not another "internet commando" spreading myths and legends, here is the source: http://saami.org/specifications_and_information/specifications/Velocity_Pressure_CfPR.pdf

That is a PDF of the SAAMI Velocity and Piezoelectric Transducer Pressure for Centerfire Pistol and Revolver.

If you look at the data, you'll see that 9mm Luger and .40S&W have identical specifications. So, as long as the round is loaded to specs, it has no more pressure than a 9mm.


Maybe the confusion comes from surface area. That's another story.

 

[Irn-Bru]

I wouldn't shoot a Shield .40 for a bet. This gun has problems, and S&W want nothing to do with it.

 

[BluGrass]

White box Winchester.

Were they the hollow point White Box? I have some .45 ACP White Box hollow points stamped Winchester.

Not sure if this would make a difference or not. I know I did not like them in my 1911 which usually shoots anything. But I have never had an issue with WWB practice/range ammo in my 1911 or my M&P FS 40.


I'd rather die on my feet than live on my knees

 

[Rastoff]

I'll bet the head stamp differences between Win and Winchester mean nothing. They probably just represent different times or different batches.

 

[Matt Butner]

Yes they were the jacketed hollow points.

I called customer service this morning at 8am. I was transferred to a manager and was then told they would not be in the office until 12:00pm. They took the serial number "again" and I left a message but have not heard back yet. I plan on emailing them also. Been busy the past two days at work and have not been able to devote the time that i would like to this.

 

[M&PmikeC]

what is the Battery part of the gun you speak of