Magazine Spring Question - MP-Pistol Forum

Magazine Spring Question

This is a discussion on Magazine Spring Question within the MP Gunsmithing forums, part of the Smith & Wesson MP Forum category; I posted the question at the bottom of this post in the Compact Forum but did not get any responses after 80 views so I ...


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Old September 10th, 2016, 04:00 PM   #1
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Magazine Spring Question

I posted the question at the bottom of this post in the Compact Forum but did not get any responses after 80 views so I forged ahead bravely, opened my magazines to compare springs, and still have a question.

- I have a some new, unused, S&W magazine springs from 8 round M&P45c mags that have light blue paint. (Original owner preferred Wolff springs)

- I would like to replace the magazine spring from a 10 round M&P45 mid-size mag that has purple paint.

- The two springs look identical (except for paint color) and have the same number of coils, wire size, and overall length. Are these springs interchangeable?

Thank You!


First Post on This Question-
"My apologies for bad google-foo. I looked at Midway and Brownells but did not find a difinitive answer. And looking for parts lists at S&Wdotcom is seriously frustrating.

Hopefully this a simple question, do the magazines for the 10r M&P45FS and the 8r M&P45c use the same spring or do they use different springs?"

Thank You for Your Help!
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Old September 11th, 2016, 07:38 AM   #2
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Quote:
Originally Posted by 4dsjw View Post
I posted the question at the bottom of this post in the Compact Forum but did not get any responses after 80 views so I forged ahead bravely, opened my magazines to compare springs, and still have a question.

- I have a some new, unused, S&W magazine springs from 8 round M&P45c mags that have light blue paint. (Original owner preferred Wolff springs)

- I would like to replace the magazine spring from a 10 round M&P45 mid-size mag that has purple paint.

- The two springs look identical (except for paint color) and have the same number of coils, wire size, and overall length. Are these springs interchangeable?

Thank You!


First Post on This Question-
"My apologies for bad google-foo. I looked at Midway and Brownells but did not find a difinitive answer. And looking for parts lists at S&Wdotcom is seriously frustrating.

Hopefully this a simple question, do the magazines for the 10r M&P45FS and the 8r M&P45c use the same spring or do they use different springs?"

Thank You for Your Help!
Is the "purple" spring used? if so, you're comparing overall length of a spring that's taken it's set to a new one, which hasn't. After it's taken it's set with use, it will be shorter than the purple one.

If both are new, give it a shot.
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Old September 11th, 2016, 10:35 AM   #3
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Originally Posted by Rick M View Post
Is the "purple" spring used? if so, you're comparing overall length of a spring that's taken it's set to a new one, which hasn't. After it's taken it's set with use, it will be shorter than the purple one.

If both are new, give it a shot.
The purple spring has been in a 10r mag that has seen very light use, maybe 20 or 30 load/fire cycles. The blue 8r springs, to the best of my understanding, were taken out by the original owner when brand new and replaced w/Wolff springs before seeing any use.
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Old September 11th, 2016, 01:33 PM   #4
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Originally Posted by 4dsjw View Post
The purple spring has been in a 10r mag that has seen very light use, maybe 20 or 30 load/fire cycles. The blue 8r springs, to the best of my understanding, were taken out by the original owner when brand new and replaced w/Wolff springs before seeing any use.
I believe that's enough for the purple spring to have taken it's set.
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Old September 14th, 2016, 06:08 PM   #5
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Thank you for the comments. Since this pistol also serves a SD role I would like to make sure that the light blue and the purple springs are indeed interchangeable. As opposed to probably working... but only for a while.

So the question about the purple spring from for the 10r M&P45FS and the light blue spring from the 8r M&P45c being interchangeable is still unanswered.
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Old September 15th, 2016, 05:20 AM   #6
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You can always try it at the range and find out if it works. They're easy to change out and at the range is where problems should be encountered.

It's amazing what one can get away with with mag' springs so don't agonize over it. But I also wouldn't use it for CCW without testing to make sure it's 100%.
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Old September 15th, 2016, 05:22 AM   #7
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You can always try it at the range and find out if it works. They're easy to change out and at the range is where problems should be encountered.

It's amazing what one can get away with with mag' springs so don't agonize over it. But I also wouldn't use it for CCW without testing to make sure it's 100%.
I wouldn't use it for carry at all; springs are very cheap.
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Old September 15th, 2016, 07:00 PM   #8
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Brian and Rick,

I agree with both of you, springs are cheap, and there is no way that I would use a spring in a SD firearm that was not correct for the magazine and well vetted at the range.

It just so happens that I have four brand new springs which may be correct for my 10r magazines. I was hoping with all the experienced M&P folks here on the forum that someone would know if the 10r and 8r magazines used the same spring.

If I don't get a solid answer I will buy the correct replacement spring for sure.

Thanks!
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Old September 16th, 2016, 04:41 AM   #9
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Spring set is a myth.
Springs dont take a set
Springs weaken with use however.
The different colors are do to the "springs rate"
Meaning the amount of pressure or weight required to compress said spring one inch.



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Old September 16th, 2016, 01:57 PM   #10
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Spring set is a myth.
Springs dont take a set
Springs weaken with use however.
The different colors are do to the "springs rate"
Meaning the amount of pressure or weight required to compress said spring one inch.
Texas40 please correct me if this is not right.

Based on your comment, that the color ID's the spring rate, then the light blue 8r springs, assuming they have a lower compression rate, might not be capable of reliably pushing up the last round or two in a 10r magazine body, even if they have an identical length, wire size, and number of coils.

Appreciate all the input so far, thank you!
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Old September 16th, 2016, 03:14 PM   #11
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Magazine Spring Question

Most likely that's correct.
Possible they would but then again they may not.
I recently had to replace the mag in my 1911 as it would not fully go to battery on the last round due to spring weakening over the yrs of use. The last round was not making it fully to the top,new mag fixed the issue.

Leaving a mag loaded will not weaken or "set" the spring.
Springs wear out due to repeated cycles NOT from being in the compressed position for extended periods.


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Old September 17th, 2016, 08:15 AM   #12
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I replaced the springs on my 12rnd 9mm. mags.The gun is EDC.
Loading the last one or two rounds was very difficult even with an Uplula.
Also seating them with slide closed was very hard.

I first cut one loop off one spring and it was still too stiff so I cut off a second loop.All OK. I then tested at range during several trips and gun worked fine.I then did my other mags and shot all at range and all OK.They have since worked fine for a couple of years.

My point is install springs and test them at range a lot. If you are then happy use them.
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Old September 17th, 2016, 05:29 PM   #13
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Quote:
Originally Posted by Texas40 View Post
Spring set is a myth.
Springs dont take a set
Springs weaken with use however.
The different colors are do to the "springs rate"
Meaning the amount of pressure or weight required to compress said spring one inch.



I Live For Myself and I Answer to No One.
Well, I guess we'll have to disagree on that, as I have personal experience with spring set, going back over 30 years; particularly with 1911 recoil spring set.

"When a custom spring is supplied longer than specified to compensate for length loss when fully compressed in assembly by customer, this is referred to as “Allow for Set”. This is usually recommended for large quantity orders to reduce cost. When a compression spring is compressed and released, it is supposed to return to its original height and, on further compressions, the load at any given point should remain constant at least within the load limits specified. When a spring is made and then compressed the first time, if the stress in the wire is high enough at the point the spring is compressed to, the spring will not return to its original height (i.e., it will get shorter). This is referred to as "taking a set", or "setting". Once the spring is compressed the first time and takes this set, the spring will generally not take any significant additional set on subsequent compressions."

Apparently, many others are familiar with spring "set" as well.
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