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Discussion Starter #1
i was surprised that my 17 rd mag can accomodate and squeeze in 1 more round plus one chambered which makes a total of 19 rounds in all. tell me it's wrong otherwise it s



a little wacky and exceptionally hi cap...



 

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Personally, one extra round isn't worth it to me for the potential compromise in reliability.



S&W didn't pick 17 at random; the magazine is designed to hold seventeen rounds and should work to their specification properly with that number of rounds. Forcing one more round in the gun could indicate (or cause) wear to the spring, damage to the follower, damage to the feed lips, etc.



Furthermore, merely being able to shove an eighteenth round in the magazine does not guarantee it will function in the pistol that way. The additional spring tension could be enough to keep the top round from feeding properly.



I'd either get the magazine checked out or mark it for range use only.
 

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Discussion Starter #5
byFieroCDSP

Wouldn't that be evidence of bending on the top of the mag? I'd be suspicious.


assure you no soft/hardware configuration done on this mag just simple squeezing thats all.



byToddG

Personally, one extra round isn't worth it to me for the potential compromise in reliability.



S&W didn't pick 17 at random; the magazine is designed to hold seventeen rounds and should work to their specification properly with that number of rounds. Forcing one more round in the


thats a very conservative analysis you got there todd...thanks.
 

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loloy said:
thats a very conservative analysis you got there todd...thanks.


No question, I tend to lean toward the conservative side on most things. 8)



I've been involved with the development and testing of a variety of handguns over the past eight years, and one thing I've learned is that serious end users are the ones who discover flaws, not manufacturers. A lot of people imagine that gun companies put their new weapons through huge batteries of tests to see how they work under every conceivable situation. Nope. Once a gun is prototyped, it tends to go through a fairly straightforward reliability/durability test series.



If you're planning to use that magazine for practice on the range, obviously it's no problem. Worst case scenario is that your gun will malf. But for carry or keeping at home, I'd really recommend against it. You just don't know what the long-term impact will be of keeping the magazine overloaded could be.
 

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Discussion Starter #7
ToddG said:
I've been involved with the development and testing of a variety of handguns over the past eight years, and one thing I've learned is that serious end users are the ones who discover flaws, not manufacturers. A lot of people imagine that gun companies put their new weapons through huge batteries of tests to see how they work under every conceivable situation. Nope. Once a gun is prototyped, it tends to go through a fairly straightforward reliability/durability test series.


most likely you've nailed it but guess what S&W said and i quote "it should not cause any damage." so now i got two different points of view both coming from the same field of expertise yet so reasonably acceptable
 

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S&W knows a lot more about the M&P than I do. I'd listen to them. :idea:



But I still wouldn't use it for anything but range practice.
 

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loloy said:
most likely you've nailed it but guess what S&W said and i quote "it should not cause any damage." so now i got two different points of view both coming from the same field of expertise yet so reasonably acceptable


If you got that from a S&W Customer service person, I wouldn't let it hold too much weight. They are in the business of customer service not Research and Development, Design, or Gunsmith.
 

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Generally speaking, don't pay too much attention to what the people who answer the phone tell you, it doesn't make any difference if they are from S&W or some other company, the vast majority of the people who answer phones like that work for a contractor, the people have a program on their computer that tells them what to say, but once in a while you get a lazy one or maybe just a little rebellious, and they just make things up, whether it has any basis in reality is pure chance.
 

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G56 said:
Generally speaking, don't pay too much attention to what the people who answer the phone tell you, it doesn't make any difference if they are from S&W or some other company, the vast majority of the people who answer phones like that work for a contractor, the people have a program on their computer that tells them what to say, but once in a while you get a lazy one or maybe just a little rebellious, and they just make things up, whether it has any basis in reality is pure chance.


I can't speak for S&W but I know from personal experience that Beretta USA and SIG-Sauer in New Hampshire both have their own in-house CS people. They aren't contractors and they don't have computer programs telling them how to handle situations.



On the other hand, it is true that many of them are not experienced gun people and their advice is often more a matter of what they've been told to say rather than anything they actually know from experience on the range or at a bench.
 

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Discussion Starter #13
bam-bam said:
Take all those .380 ACP rounds out of your mag right now before you break something!


hehehe!!!
not all just one. thanks for crying out loud.
 

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Discussion Starter #14
Dan Burwell said:
[quote name='loloy']most likely you've nailed it but guess what S&W said and i quote "it should not cause any damage." so now i got two different points of view both coming from the same field of expertise yet so reasonably acceptable


If you got that from a S&W Customer service person, I wouldn't let it hold too much weight. They are in the business of customer service not Research and Development, Design, or Gunsmith.[/quote]



ToddG said:
Personally, one extra round isn't worth it to me for the potential compromise in reliability


i have not seen whats really inside my mags, i pressume you have fieldstripped your mags or at least have seen its schematics. let us break down the process a little deeper and more technical this time when follower is depressed spring coils come closer to each other until the 17th therefore leaving small amount of space in between coils right? if one more round is squeezed in would there be a chance that spring coils get crushed to its side and get entangled by itself unable to release its potential energy when pressed to its max? is this what compromises reliability you're talking about? or just plain simple anticipation of possible failure?
 

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Ok, here goes.



some mags WILL fit an extra round over what they are specced for. Sometimes this is because they cahnged something since the spec was set out. For example CZ75 15 and 16 round mags, there was a follower change and for a while you could buy "15" round mags, and they all seemed to hold 16.



This is not the case with the M&P. The reason you can cram an extra round in theres is likely because you are doing one of several things.



First, and most probably, is that you are muscling the last round in, and slightly distorting the feed lips. Over time, this will likely cause malfunctions later because the feed lips have become out of spec. Common results form this in a pistol would be having a live round flip up 2with the case rim still retained by the feed lips when trying to feed. You will note in your picture, the round does not appear to be flush with the rear of the mag. Thus the rear will have proper tension, and the front won't. This usually results in a death jam, where you have an extracting round and a live round vying to occupy the same space. To clear it you ahve to brute force the mag and the gun apart.



Second, in a magazine design liek the M&P where it is basically a single stack at the top and a double farther down, you can cause the single stak width coils to kink and bend over in the double wide section of the mag tube. This leads to spring fatigue at least. It can also cause the follower to tilt over and jam in the mag tube. Given the M&P design, I don't think this failure mode is terribly likely as the desing mitigates some of these issues (i.e. length of the single stack widht coiled section of the spring, anti-tilt legs on the follower, etc.





Then of course you have the problems it may cause from simply not operating the thing right. If you notice, the cartridge doesn't seem to fit flush with the rear. Ths can cause you to be unable to seat the mag in the gun when the slide is forward. you reload with this, and you may get a failure to xrtract because the rear of the extracting shell catches on the edge of the improperly positioned bullet. Etc. Then of course there is the ammount of pressure on the spring. If it is completely compressed, there is no give other than the mag lips. Which only give upwards, not downwards. You jam it in the gun and make it latch, you may actually cause a jam from too much friction on the slide. Have you tried shooting with your mags loaded to 18? Take apart your gun and check the bottom of the slide for a nice brass stripe. If you see one, think about where that is coming from and why. Then of course, there's the worst case scenario. That you are shooting something that is a hot round, and you ARE causing interference, but rather than a jam, you start getting bullet setback on your very hot +P+ round. 9mm is a nice strong case, but you could still get a nice kaboom, or a blown primer and some hot gasses back in your face out the rear end of the gun.





All of the above are conditions taken from real world guns except the kaboom/hot gasses. The person that happened to was forunately shooting mosue fart loads, so all they got was some extraction issues from the increased pressure and some really flat primers.



The guns that contributed to the above list of crap that can happen due to mag problems are STi .40 mags with .38 super springs in them, and other fat 38 super mags without proper tolerances. STI ls-9, walther p99, cz 75b, various 1911s in .45 acp, and a few others I can't recall off the top of my head.



However, you are free to do whatever the hell you want. But I'll piint out that if round 18 is not flush againt the back of the mag, it DOES NOT FIT. Despite what you would like to believe.





ETA: Oh, and the reason why S&W says they it won't hurt is that they don't consider it warranty voiding behavior, and don't know you will actually harm anything in particular. So if you break it, just send it in. That's WAY different than being told.. yeah it works just fine. If it worked just fine, it'd be in the manual and listed as the specced capacity by the engineers who designed it. What you know is that it isn't on the list of things labeled "DO NOT DO" for the CS FAQ.
 

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I was a mechanical engineer in a previous life, at least by education. When you push something beyond the limits of what it's designed to do, you cross into an area somewhere between "safe" and "sure to fail". Because engineering must account for quality of manufacture, operator factors, quality of materials, you sometimes have to just "fudge it" and put in a factor of safety, a cushion, to stack the odds in the operator's/customer's favor that the thing will work like it's supposed to, and do it safely. Cramming another round in there may be physically possible, but there are dozens more reasons not to do it, and only one reason to do it, and that's to gain one round of capacity.



I find it odd that the OP even has to ask if it's wrong, considering their signature would imply they would have the common sense not to.
 

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Discussion Starter #17
raz-0 said:
However, you are free to do whatever the hell you want. But I'll piint out that if round 18 is not flush againt the back of the mag, it DOES NOT FIT. Despite what you would like to believe.


snuggly fits and looks the same with the 17th but slides a bit stickier shaving off the brass a little against mag lips nevertheless your points are superlative, highly cautious and technical. well taken...thanks.
 

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Discussion Starter #18
Chessie724 said:
I was a mechanical engineer in a previous life

I find it odd that the OP even has to ask if it's wrong, considering their signature would imply they would have the common sense not to.




thats entirely the point of this thread its wrong but better back it up for the common good. welcome back to earth...
 

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You're probably over-compressing the spring when you try to squeeze too many rounds into it. Over time, although I'm not sure how much your mag springs will probably not reliably feed rounds. Also might put extra pressure on the feed lips. At $30+/mag I think I'll stick with 18 rounds (17+1). I don't think that the extra hollow point or two is going to make much of a difference if I've already unleashed 18 rounds.
 

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Discussion Starter #20
thedude said:
You're probably over-compressing the spring when you try to squeeze too many rounds into it. Over time, although I'm not sure how much your mag springs will probably not reliably feed rounds. Also might put extra pressure on the feed lips. At $30+/mag I think I'll stick with 18 rounds (17+1). I don't think that the extra hollow point or two is going to make much of a difference if I've already unleashed 18 rounds.


very conservative guy, you just pushed the right button dude, thanks. :wink:
 
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