.40 Shield Kaboom

[Llando88]

9mm Luger and 40 S&W both have SAAMI max pressures of 35,000 PSI.

So - some other reason for the .40 Kabooms?

Could be; Cartridge diameter relative to the chamber surround -- I.e. 9mm chamber supports more "%" of the rear of the cartridge? Leading to a "higher" relative chance of a one in a million load leading to a Kaboom in a .40, vs. the 9mm?

Just asking out of interest.

Also to remind all to wear eye protection. Can't say that enough times.

OP - Get well soon.

 

[peterthefish]

Wrong. Simple case ruptures due to excessive chamber pressure. If the chamber was "unsupported" the gun would kaboom the first time it was shot.

If you're afraid of the gun, instead of making unsubstantiated claims, sell it. You'll find plenty of ready and willing buyers here and elsewhere.

Very much this. All should bear in mind that firearms are tested with a proof round that well exceeds SAAMI spec. Moreover, the web at the base all brass is always a good bit thicker then the walls.

Many barrel designs provide less than full case support without any issue. It is generally a compromise made to improve feed performance. With an in-spec round with fresh brass it is not a problem.

With an over pressure round (or bad brass) it can be. I have an FNP-45 Competition which is has less case head support than many other 45s - the FNX-45 improved upon this, but the FNP can 'Glock' brass.

I never had an issue with factory ammo in the FNP, but throw in a standard pressure load where the brass is poor quality to begin with and then had been work hardened a bit too much and you get this;



That kaboom blew the mag out of the gun and apart, and also blew off the safety and mag release. And that is with the much lower pressure .45.

Whether or not better case head support would prevent a similar failure in the event of an out of spec round is, I think, an academic question at best. A firearm is designed to shoot in-spec ammo and we cannot expect designers to accommodate every and any deviation from spec someone can dream up.

 

[Rastoff]

Wrong. Simple case ruptures due to excessive chamber pressure. If the chamber was "unsupported" the gun would kaboom the first time it was shot.

Not necessarily. The chamber/round is clearly unsupported. The pictures posted above show that. In fact, all pistol chambers are unsupported to some degree. The question is, how much?

Sure, this could have been due to an over charged round. Would it have exhibited this same problem in a fully supported chamber? Maybe.

The small amount that is unsupported will usually allow an average case to fire without damage. Let a case get in there that is on the thin side of the tolerance and I can see how it could rupture at the unsupported part, even under normal pressures.

There is another thread where an owner has had every case in his 9mm Shield bulge at the base. He's sent it back to S&W twice already and they claim it's normal; bulging cases is not normal. His is just an accident waiting to happen.

Even though both cartridges develop the same chamber pressure, approximately 35,000 psi, the larger surface area of the .40 means it has to handle more pressure in the unsupported area than a 9mm would.

 

[feelinlucky]

Smith and Wesson or any other gun makers would never open themselves up to the liability from marketing a gun that would not handle the standard and +P SAAMI specified pressures plus a healthy safety margin.

You are certainly free to think this is a defective design if you like. I doubt you are going to convince too many people here though.

Perhaps a revolver would be a better choice for you.

 

[Roger S&W]

Smith and Wesson or any other gun makers would never open themselves up to the liability from marketing a gun that would not handle the standard and +P SAAMI specified pressures plus a healthy safety margin.

You are certainly free to think this is a defective design if you like. I doubt you are going to convince too many people here though.

Perhaps a revolver would be a better choice for you.

What are your thoughts on the comparative pics in post#83. The M&P40c and Shield 40 chambers side by side? I understand gun manufacturers make design compromises, etc for functionality but that 40 Compact chamber is the way it's supposed to be I would think.

 

[Rastoff]

I'm not trying to convince anyone of anything. I'm merely discussing what I see here.

I am curious though. The 9mm and .40 in both compact and full size are great guns. Why change the design of the feed ramp in the Shield?

 

[Roger S&W]

I'm not trying to convince anyone of anything. I'm merely discussing what I see here.

I am curious though. The 9mm and .40 in both compact and full size are great guns. Why change the design of the feed ramp in the Shield?

Probably like someone mentioned earlier. S&W found during testing of the Shield, that feed ramp/chamber design led to increased reliable feeding.
Same reason Glock used a similar design all those years and gained a stellar reputation for unquestionable reliability.

 

[Rastoff]

Yes, I suspect it has to do with feeding.

Same reason Glock used a similar design all those years and gained a stellar reputation for unquestionable reliability.

Remember, Glock had several "kabooms" with their earlier guns. They have updated their feed ramp/chamber to support the round more. At least my Glocks had better supported chambers than we've seen here in the Shields pictured above.

 

[HeyMikeyE]

40 S&W Bulging

There is another thread where an owner has had every case in his 9mm Shield bulge at the base. He's sent it back to S&W twice already and they claim it's normal; bulging cases is not normal. His is just an accident waiting to happen.

I experience some bulging with nearly every 40S&W I shoot through my SD40VE. I had read enough about this "common occurrence" even before purchasing my gun that I was confident that there was nothing to be concerned with. I understand that there are even more makes of semi-auto 40's that are reported to bulge the casings.

There are even special dies that are readily used to remove the bulges prior to reloading 40S&W casings.

If you are referring to only 9mm bulging being a problem then that may very well be the case. I haven't read anything about that.

Mike

 

[feelinlucky]

What are your thoughts on the comparative pics in post#83. The M&P40c and Shield 40 chambers side by side? I understand gun manufacturers make design compromises, etc for functionality but that 40 Compact chamber is the way it's supposed to be I would think.

Definitely a design difference. Safety compromise? No. Look at the photos in post #85. You'll see quite a bit of variation in those chambers too. If S&W has created a dangerous gun, then so have several other gun makers.

I said earlier that I created some loads that were too hot. They were clearly over any SAAMI specifications, dangerously so. The cases bulged when I fired some of them in my Shield. The cases also bulged when I fired some of them in my Kahr PM40. These rounds could have caused a kaboom in either gun.

So do I think either of these guns is defective? No. But you can clearly see that no gun design is safe from this kind of defective ammunition.

 

[Rastoff]

If you are referring to only 9mm bulging being a problem then that may very well be the case. I haven't read anything about that.

Mike

No, not pointing to just 9mm. I see this as a problem to be solved rather than ignored. I've heard of sizing dies specially designed to take this bulge into account.

I guess I'm too progressive. feelinlucky seems to think that bulging cases should just be ignored. I see it as an issue that could be improved. I have never personally had a case bulge on me or a handgun blow up. Is it dangerous? Maybe not, but there is certainly an issue here.

 

[feelinlucky]

Yes, I suspect it has to do with feeding.


Remember, Glock had several "kabooms" with their earlier guns. They have updated their feed ramp/chamber to support the round more. At least my Glocks had better supported chambers than we've seen here in the Shields pictured above.

Not so. Look closely at a picture of the older 40 Glock chamber. You'll see that the Shield chamber is well supported compared to it.

 

[Maximumbob54]

I'm still picking up my Shield in .40SW tomorrow afternoon.

 

[feelinlucky]

...feelinlucky seems to think that bulging cases should just be ignored. ....

Perhaps you should try to avoid getting personal, and not presume to speak for me.

 

[Roger S&W]

I just chamber support checked 5 barrels in the VERY bright SW Florida sunshine. I'll give you the run down from worst to best.
1) G23 old barrel from 1999 - Terrible support. Could definitely see the "Glock smile" being made on casings. (although my gun never blew up all those years of shooting factory ammo)

2) G23 new barrel -(2013) Much better support. Still see a tiny bit of the casing on the bottom. Tiny.

3) M&P Shield 40 - About like the new G23 barrel. Tiny miniscule amount of casing seen on bottom. Doesn't look as dramatic as photos taken by pitbulloncrack.

4) FN FNS-40 - Excellent full chamber support.

5) M&P40c - Excellent full chamber support.

Note: I decided I'm going to fire my Shield 40. If I see any smile or bulging AT ALL on the casings. Goodbye. That's just unacceptable to me.

 

[Rastoff]

Perhaps you should try to avoid getting personal, and not presume to speak for me.

Who's getting personal? Didn't you say that you thought this was not a design flaw?

Not so. Look closely at a picture of the older 40 Glock chamber. You'll see that the Shield chamber is well supported compared to it.

You missed the part where I stated that Glock has updated their chamber/feed ramp design. Roger S&W supported that with his previous post.

 

[vipermd]

I have heard the "unsupported chamber", "bad brass", "hot load" and all seem to focus on that point as though it is fired in a vacuum. Any engineers that would like to shed some light? Smith & Wesson fired how many rounds after the 10 mm was deemed to powerful, and developed the 40SW. I do not recall seeing any 3rd gen 40 Kabooms, any one have any documented? , I need to pull one out and compare the chambers. Could this be the result of "voodoo and Polymer" stresses compared to steel/Aluminum? Bad Brass? High Pressure? Chamber? Polymer? or the perfect storm with all of them? Be Safe,

 

[feelinlucky]

I just chamber support checked 5 barrels in the VERY bright SW Florida sunshine. I'll give you the run down from worst to best.
1) G23 old barrel from 1999 - Terrible support. Could definitely see the "Glock smile" being made on casings. (although my gun never blew up all those years of shooting factory ammo)

2) G23 new barrel -(2013) Much better support. Still see a tiny bit of the casing on the bottom. Tiny.

3) M&P Shield 40 - About like the new G23 barrel. Tiny miniscule amount of casing seen on bottom. Doesn't look as dramatic as photos taken by pitbulloncrack.

4) FN FNS-40 - Excellent full chamber support.

5) M&P40c - Excellent full chamber support.

Note: I decided I'm going to fire my Shield 40. If I see any smile or bulging AT ALL on the casings. Goodbye. That's just unacceptable to me.

Really hot +P ammo would probably bulge a little in an old G23 barrel. Any bulges or smileys in any of those other guns would indicate ammo over safe limits.

If you use good consistent quality factory standard or even +P ammo in a Shield, you likely won't see any bulges or smileys. If you do, I'd be interested in hearing about it. The only time I've ever seen bulged brass out of my Shield was when I fired some of my handloaded ammo that was way too hot. Needless to say, I ceased using that ammo when I saw the pressure indications. If you use WWB or some equivalent, or handloads of unknown history or quality, all bets are off.

BTW, it's not as common, but 9mm or 45acp will also bulge or kaboom if it is too hot. Look at some of your 9mm chambers.

 

[OakleyFreak]

I will add this
When my sons gun (9mm Shield) came in.
The spent shell that S&W has in a little envelope with a signoff signature.

Well it had a small bulge in ?????
My son and I were a little taken aback.

And of course the first 50 rounds shot threw it confirmed that S&W must have known of this issue.
I am waiting 5 days to hear back from them.
I almost bet that they are willing to accept a certain amount of returns as part of doing business.
That would explain the spent shell having a slight bulge.
My theory anyway

 

[emory]

I have posted this image before regarding chamber support in the .40 shield, but it seems relevant here as well. Note the gradual change in the wall thickness of the brass at the depth of the feed ramp cutout into the chamber. FWIW, I have ~1300 rounds through my Shield .40 with no bulging brass