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According to the rumors, certain firearms do not have fully supported barrels, thus the 40's bad rap for kabooms. Designers feel as long as the loads are loaded to specs, and the barrels are fully supported, kb's are a thing of the past. So does anyone know if the M&P has a fully supported barrel, or one that supports the case completely. I would assume it does, but thought it would be interesting to hear others' opinions.
 

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Although I think most of the .40 kabooms are attributed to other issues; yes, the M&P chamber is fully supported.
 

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Fully-supported, it seems.

Sure looks that way to me.



This is one reason I got an M&P instead of a Glock 22 or 23. That, and the conventional rifling, which means I can use lead bullets if I wish. Both characteristics together mean I can shoot relaods without KB! worry - assuming I don't get stupid and double charge a case. Not that I've ever done that. No sir, not me. Especially in .45 ACP.
 

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YukonGlocker said:
Although I think most of the .40 kabooms are attributed to other issues; yes, the M&P chamber is fully supported.


Really? Everything I have found points to unsupported chambers or reloads from brass fired through unsupported chambers as being a major factor in most (not all) kB. There are others, of course (like barrel blockage, over seated rounds, etc...) but most had a link to unsupported chambers.



I would be interested in reading documentation that points to other causes so that I can get my facts straight.



MI_Jester
 

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Glock barrels



 

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Fully supported chambers give you more room for error/margin of safety than an unsupported chamber. A fully supported chamber, however, is not kB!-proof.



Too, I think fully supported chambers make it easier/safer for reloaders as the brass does not get as stretched/bulged.
 

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The fully-supported chamber, another reason the M&P is better than the Glock!
 

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i've heard that Glock are now making their .40's with supported shambers. ::Shrug:: It's just something I've read on Glocktalk. I still prefer the M&P, and I shoot 9mm anyway since I'm a cheap miser.;>



Ciao,

Effy
 

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AFAIK there are no true "fully supported" semi-autos. Just some are more supported than others.



Before you blast me, think about it. A revolver is fully supported. The cylinder fully supports the sides of the case. That won't work in a semi-auto for obvious reasons. There is always a bit of a gap in coverage by the feed ramp on a semi-auto.



Now Glock, erring on the side of reliability supported the chamber less than many other makers. This combined with early Federal brass that had weak case webbing is what gained the Glock .40 it's kB reputation. Reloaders, who used brass far too often considering how much the brass expands given the Glock's support, kept the kB reputation alive by using brass that should have been discarded or by double charging loads. (The only Glock kB I have personally witnessed was due to a double charge.)



There was also the theory running around that 180gr .40 cal loads that were chambered multiple times and suffered some bullet setback, would increase the chamber pressure to the point of a kB. I'm not sure how valid that is, but it's out there.



My understanding is that Glock has since redesigned their .40 barrels to have more support. That's a good thing, IMO. It definitely increases the safety margin. However, if you use factory loads, excepting the early Federal stuff, and used new brass when you reload then the kB hype was over-hyped, IMO.
 

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I doubt if any semi auto pistol actually has 100% support, it would probably have difficulty feeding reliability problems. While quite a few of the Glock KB's can be traced back to reloaded ammo, there have been quite a few with good quality factory ammo also, some has been federal, and some wasn't, the photo above is PMC factory ammo and PMC was good quality ammo, the primer sealant visible in the photo shows this isn't reloaded ammo.



It's hard to know how many of the KB's might be related to bullet setback, I'm sure at least some, some people just keep chambering the same cartridge over and over again, they might have noticed some setback but not know how serious that can be.
 

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G56 said:
some has been federal, and some wasn't
The Federal ammo was in the 94-95 time-frame. IIRC, it was mostly limited to Hydrashocks, or whatever they called them then.



Even quality ammo makers put out bad loads from time to time. It's important to remember that, IMO. It is a dangerous sport sometimes.
 

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Since all semi-autos are modified Browning designs they are also all "partially" supported chambers. A fully support chamber in a semi-auto would not feed reliably if at all.



I've had a case rupture at the 6 o'clock position in my USP so no semi-auto is immune to it. The first time some M&P owner reloads 40 S&W on brass that's been used too many times we'll see here as well. It's just a matter of time.
 

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m4arc said:
... The first time some M&P owner reloads 40 S&W on brass that's been used too many times we'll see here as well. It's just a matter of time.


And reports will be all over the internet about how bad the M&P barrels are. :wink:
 

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YukonGlocker said:
[quote name='m4arc']... The first time some M&P owner reloads 40 S&W on brass that's been used too many times we'll see here as well. It's just a matter of time.


And reports will be all over the internet about how bad the M&P barrels are. :wink:[/quote]



Yep, just like the first time an M&P owner has a ND and claims, "it just went off!"







:wink:
 

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m4arc said:
Yep, just like the first time an M&P owner has a ND and claims, "it just went off!"







:wink:
But would he be the most professional person in the room?



"I am the only one in this room professional enough to handle the Glock 40!" BANG!
 

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I'm not sticking up for Glock and I'm not bashing anybody. But I took the barrel out of my Glock 22 and droped a round in it. It looks just like the M&P picture on here. It's supported a lot more than the Glock barrel in the pic posted on this thread. It's a 3rd generation if that matters.
 

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Glock tightened the chambers on all the .40 models. They initially had some feeding problems (just a few here and there), but I think they are working great now.
 
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