Explain this to me.

-We are told to replace the recoil spring after 5,000 or so rounds.

-I just read advice to a new semi owner to lock back the slide to intentionally weaken the spring and make it easier to rack the slide.

How are both of these statements compatable?

Locking back the slide will do diddly to "untighten" it. 5,000 round recommendation is a conservative one to keep your gun running flawless. Realistically it's well before you'll have any issues so long as you're not using .357sig.

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unrepentant M&P fanboy

The 5k mark is probably a good point to start watching for possible problems related to a weak recoil spring such as occasional failure to go into battery. If it's working the way it's supposed to there's no reason to change it. On the other hand some just change it out as cheap insurance. Your choice.

The advice to weaken the spring by locking back the slide to make it easier to rack is pure nonsense. If this is a problem the solution is to do hand and arm strength exercises.

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USAF, 69-92
Vietnam, 72-73

I believe S&W recommends replacement of the recoil spring to its agency customers at about 5,000 rounds, and the trigger return spring (the one with the "tampon" inside) more frequently.

I really wish S&W would provide the following for the M&P, which I think is vitally important if the M&P is to have a chance at besting the Glock:

(1) Much better availability for parts and armorer's tools, including sight pushers and replacement sights.

(2) Varying heights of front sights that are (a) actually available; and, (b) more easily replaced. Along with this one would also go a more easily adjustable or replaceable rear sight as well.

(3) More armorer classes offered with more frequency and in more locations, that are open to dealers, individuals who want to learn and to gunsmiths, as opposed to just agency customers.

Yes. Available Tools and Support to maintain your firearm is the mark of serious firearm manufacturers.

Some good points.

As far as the trigger return spring (with the fiber insert), in my recert class they were still only recommending replacement at the same frequency as the recoil, mag & striker springs, which is their conservative 5K/5yr interval. They've been tested to much longer intervals, but they tend to take somewhat of a conservative approach to these sort of things is guns used for dedicated defensive roles.

The armorer tools are simple, although S&W has standardized their tools for the plastic pistols into a general tool kit, for an affordable price to armorers. http://www.smith-wesson.com/wcsstore...tolToolKit.pdf.

I've found the newest of the MGW sight pushers for the M&P to work well enough.

Sights? The company has been working with different companies to increase sight options for the M&P (regular & Shield).

The armorer classes? As with the 3rd gen pistol armorer classes, the M&P armorer field classes are given by both the academy armorer instructors and at least some LE sales reps. I was thinking about applying to become an armorer instructor, and looked into it. Lot of traveling, though.

Field classes are both those scheduled in advance, open for sign-ups, and those "unscheduled" classes provided to LE agency customers. Sometimes it's possible to get a seat in one of those, if you know someone doing thee scheduling at the agency and they don't mind adding a seat (and it helps sell the guns to any other potential interested agencies in the area).

Dunno about opening up the classes to other than the LE/Gov, Mil, Security & gunsmiths who are warranty stations or support an agency's weapons, meaning the folks they've previously allowed to attend, but then they'd really need more instructors.

Considering the numbers of folks who have joined S&W from other guns companies, I've heard it's possible some of that type of marketing may be being discussed for the future change, like opening up armorer classes, as well as changing how parts are sold. Obviously these sort of changes are going to involve careful scrutiny by corporate management, as well as corporate legal.

Guess we'll see.

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Ret LE Firearms inst & armorer

I don't think so. Well, not "pure" nonsense anyway. I don't believe it will make a significant difference though.

I've heard the same person (not you moxie) say that a spring won't lose any strength by leaving it compressed and then say that leaving a mag loaded for a while will make it easier to load. Obviously these are conflicting remarks.

I know that leaving a spring compressed will cause it to lose some of its strength. I know this because I've seen it in torque wrenches. As a Metrologist I've calibrated thousands of things like torque wrenches. If left compressed, the torque wrench will most likely be out of tolerance when tested.

Even so, that experience alone is not enough to satisfy most people. So, I've started an experiment. I've actually taken two springs. One spring is compressed and one is left alone. Here is my rig:

The springs


The test rig


The object is to show that a spring, when left compressed, will lose some of its strength; or not. I set this up in June of 2013. I will take the spring out June 2014. At that time I will measure the springs again. At that time we will see if they are the same or different.

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Freedom isn't free.

No kidding. Some folks don't see the contradiction, do they?

Even the gun companies and spring vendors & makers are aall over the place on this subject.

I look at it like this ...

I've seen a LOT of malfunction & stoppages during quals & training sessions over the years that were directly attributable to weakened & worn-out mag springs.

The significant number of these instances involved personally-owned pistols, and the owners typically stated that they only fired those guns when required to do so (agency quals or CCW renewals). To put more simply, they just left the mags loaded between infrequent range sessions and weren't constantly loaded/unloading the mags (by shooting, cycling ammo, etc).

I've sat through more than 20 armorer classes, at least a dozen of which have involved semiauto pistols of one make or another. I can't think of a single class in which I haven't heard some other armorer, or a factory rep or instructor, discuss how someone discovered the hard way that mag springs had become too weakened to provide normal functioning in a duty or off-duty pistol, and the user/owner wasn't a frequent shooter, but had simply left the mags fully loaded for various lengths of time.

Add in the 5 AR armorer classes I've attended, and that makes for even more instances where armorers & instructors have related more instances of feeding/functioning issues related to weakened mag springs. Sometimes the weakened springs had been used a for a lot of shooting, and sometimes they'd just been left fully loaded for a long time.

Toss in the 870 armorer class, and we can add even more instances of mag springs reported as having becoming weakened after having been left fully compressed over time.

Even I can sometimes start to take a hint.

Now, some related thoughts ...

Not all springs are designed the same, made of the same materials, hardened the same or are used in the same mag body designs.

When a gun maker receives a case of 10,000 mag or recoil springs, do you really think that the spring maker took the time to function test each and every spring on some equipment to confirm tension? Maybe batch testing. But think about the relative cost (inexpensive) of each spring, and then wonder about the tolerance range that's considered acceptable when making different types of springs. Do you really think each and every 1911 spring that's rated at 16.5 lbs or 18 lbs produces that weight?

How about any nicks, cuts, bend, kinks, coil deformations or other conditions that may be introduced (albeit unknowingly) to the spring? How about a spring that was produced on the lower end of whatever the acceptable spring rate was considered to be, and then has to overcome conditions like dirty mag bodies?

How about unknown material or heat treating problems that may not surface until the spring has been put into service?

I've seen (and experienced) some mag and recoil spring last longer than might be fairly expected, and then I've seen others fail to exhibit normal strength and service much sooner than I'd expected. That's why I check them periodically, which includes some different "bench checks", as well as observing their function each and every time I use them at the range.

When manufacturers have made recommendations about spring service life and periodic replacement intervals, I've given those recommendations careful consideration ... even if & when those guidelines may change from one class to another.

Properly rated recoil, mag & striker springs that remain within their intended service condition are crucial to the optimal functioning of a semiauto pistol. Obviously, other springs are also important (trigger springs, plunger springs, etc), but the recoil & mag springs are things that the average owner can replace for themselves.

Where do you want to cut corners and scrimp?

I don't like to wait for a tire to pop off the rim when I'm driving my car or motorcycle before I think to check the air pressure (and add air) ... or have the engine seize before I check the oil level ... or check the coolant level, etc.

BTW, Rastoff, have you considered trying a couple other springs for your informal test? I know you have only so much in the way of tools and floor/shelf space.

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Ret LE Firearms inst & armorer

That's pretty radical Rastoff but I admire your quest for knowledge.

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Audemus jura nostra defendere

Sure not scientific but has real world connotations and the sampling is of 62 Glock 17's 55+ were all purchased at the same time.

After over 10 years my dept moved from G17 to G22. I took all of the 17's in and issued 22's. This included the magazines. According to my predecessor no magazine was ever replaced nor were any mag springs. Most of the mags were in duty rigs compressed with 17 rounds their whole working life. You could sure tell they were softer than new; mushy is the term I use. BUT none failed to feed the next round. So serviceable was the word. Weaker?? I don't know if weaker or if they simply took a set and responded from there.

I wish I knew where it was but there was a study done by mil on M16 mags and the determination was an unloaded spring and loaded spring were equal in strength but a spring that was loaded and unloaded and loaded with the process repeated over time would weaken before the always loaded or always unloaded spring....make sense?

I've seen a guy with a personally-owned G22 that exhibited repeated feeding stoppages related to mag spring weakness. he said his gun was 110 years old and had never had the springs replaced. He also said he left the springs fully loaded (duty weapon used at another agency), and only shot when he had to shoot, and waffled a bit, saying sometimes once a year.

I strongly urged him to respring the gun. He said he'd ask his agency's armorer about springs ... and that the weakened springs probably explained why his G22 had jammed a few times when he'd been trying to shoot an attacking pit bull a couple weeks ago.

I had the guy come through our range about a year later, at which time his extractor and recoil spring assembly broke, if I recall correctly.

A couple of our guys on a special enforcement unit like to carry personally-owned G27's loaded with G23 mags. I can think of a handful of instances when their guns started experiencing feeding stoppages when being used with the G23 mags, but when they switched to the stock 9-rd G27 mags they ran fine. I remember asking one guy how long he'd had that G23 mag in his gun, and he said 3 years. He shot quarterly, as I recall, so it's not like it was being emptied and loaded for a long of shooting.

I suspect that mixing longer mags in shorter guns (usually involving lighter slides & increased slide speeds, and sometimes shorter slide travel, even if different recoil springs are involved) may be a factor at times.

So, too, would be the recoil forces for different calibers, driving the slide velocities. I'd not be surprised to see some 9's & .45's (excluding 1911's) run longer on springs than .40's & .357SIG's.

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Ret LE Firearms inst & armorer

Torquing the longer mag (applying frontal pressure) in the shorter grip with their pinky while gripping the weapon can cause problems. This sometimes results in the mag tilting forward just enough to cause feeding problems depending on ammo used. Running fine with the shorter G27 mag is a good indicator that it's probably the issue.

Yep, it can. Didn't seem to be the issue here, though. These guys were also using the extended sleeves, FWIW.

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Ret LE Firearms inst & armorer

I'd love to see how this experiment turns out if you were to take the spring out now and test it, then put it back in and see if it makes any difference by next year.

I ask to take it out now because many talk about "setting" a spring, meaning after it is initially compressed it will weaken to a certain point and then weaken no more if it's left compressed. At that point it's cycling that weakens the spring, at least theoretically that is how it works.

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unrepentant M&P fanboy

That's either a typo or the guy is pulling your chain.

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Minimize the variables

Interesting, were they soft or hard sleeves?

I agree with the above tangent to the test. I see a lot of people stating to lock the slide back for a few days (or a week) claiming that amount of time is sufficient to correct assumed deficiencies linked to a stiff spring.

Rastoff,
My comment re the advice to lock the slide back, etc., was not aimed at the technical aspect of a compressed spring losing its power, it was aimed at the concept of weakening the spring so as to make racking the slide easier. Hence my advice to exercise more.

I'm fully on board with your statement that leaving a spring compressed does make it lose strength.

I first became aware of that in Vietnam. As a weapons safety inspector I found that many armories were storing hundreds of 1911s on pegs, for many months, through the trigger guard with the slides locked back. Nice for safety but lousy for functionality. Many of these 1911s exhibited problems with failure to go fully into battery. I tested some of these myself. Clean, well-lubed, pistols with issue ammo. Chronic failure to go fully into battery. Had to bump the rear of the slide. Change the recoil spring and voila! No problem. The conclusion was obvious and became part of my recommendation to units who stored guns with the slides locked back. Change the springs at some pre-determined interval to counter the effects of the springs being compressed. It works.

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USAF, 69-92
Vietnam, 72-73

Springs are designed and heat treated so that they return to their unstressed position. If a spring is compressed, and held compressed, it will "slowly" fatigue and cause loss of pressure. However the condition that causes the fastest fatigue and weakening of coil springs is cycles of compression and decompression. This is what happens to the recoil springs as the slide cycles when shooting.

Think of bending a bare copper wire. Bend it a few times and no problem, but bend it back and forth rapidly, the copper generates heat and will eventually fatigue and break. Spring steel, depending on how it was designed and heat treated, should withstand many cycles before it starts to fatigue, and many more cycles before it will break. But like all mechanical things, that spring could be defective and could fatigue or break well before its designed lifespan.

Bob

Bob, you make the most sense of those I've talked to about this. Alas, many are close minded on this subject. I've long held that springs will compress over time, but that ammount may be insignificant to the operation of a gun. Even though it is measurable.

I'm not going to take the spring out of the jig until June 2014. It would compromise the integrity of the test. All I expect to see is a shorter spring when uncompressed.

Neither am I going to add other springs to the test. If this spring will do it, then all springs will do it. Sure, not all springs will respond the same. Remember, the test is done for those who say a spring will not lose strength by just sitting compressed. They maintain that it only loses power through repated compression and extention.

The test is already compromsed a little. I was supposed to leave the country for a year. That would ensure I couldn't touch it for a year. I broke my leg and they wouldn't let me go. So, you'll just have to trust me that I won't touch it.

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Freedom isn't free.

Egads, that as great.

I've beeen using a borrowed laptop while traveling, and I've been getting a LOT of double-taps on some of the keys. (I left in the 3 e's I just noticed at the beginning of this sentence as an example. )

I've had to make sure I go back and check when I've been typing the word "as", as I've unintentionally, and unknowingly, added an extra 's' more than a few times.

Thanks.

(I'm still chuckling ...)

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Ret LE Firearms inst & armorer

Hard, as I recall. They make soft ones? Oh brother ...

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Ret LE Firearms inst & armorer