Springs and things

[GaryS]

I have a couple of 6906 magazines which could use new springs. I prefer OEM springs, which seem to have become extinct.

I had my Brownell's account set to alert me when they came in as they were listed as out of stock. I was surprised when I received an email this morning telling me they were in stock. I clicked on the link only to find that they were no listed as no longer available.

My only option appears to be Wolff 10% over power springs.

Is there any downside to using these? Conversely, is there any advantage to using these? Are there any other options?

 

[gmborkovic]

How many rounds do you have to run thru a mag to cause fatigue?

 

[GaryS]

I don't know, however I also don't know how may the previous owner(s) may have run through them or how they were stored. Same with recoil springs. Which is why I replace them as well.

How many rounds do you have to run thru a mag to cause fatigue?

 

[gmborkovic]

Gary, I didnt know the mags were previously used. I assumed they were new, What does how they were stored play any part in this.

 

[Walter Rego]

Springs and their service life get discussed fairly often. From what I have read from people who seem to be in the know, is that properly made and tempered springs "break in" a little when first put into service, and after that it is the number of compress and release cycles that determines service life. Not from leaving magazines loaded for a long time for example.

I can attest to that fact that new springs do need to be "broken in". For example, my Kahr K9 magazines have very stiff springs. They were very difficult to load the first 6 or 8 times, I even resorted to using a loading tool. Now they are still stiff but I can load them completely without undue stress to my thumb. Same deal with fitting a new recoil spring to a 1911 type pistol for example.

All of that said, I have all new Wolff springs in my Model 1006 including their extra power magazine springs and I have encountered no problems what so ever. I also have Wolff extra power magazine springs in my pre-Model B CZ-75 and they too are not a problem. Other than being pretty stiff to load.

I would go ahead and change out all the springs on your Model 6906 and fire a few magazines full just to verify functionality. I think you'll be just fine.

 

[GaryS]

At this point it's probably safe to assume that just about any 3rd Gen magazine is used.

For the magazine body, there's probably no difference in how they were stored absent being in extremely humid environments. As for the rest, I consider springs, followers, and baseplates to be items that will need periodic replacement.

Gary, I didnt know the mags were previously used. I assumed they were new, What does how they were stored play any part in this.

 

[GaryS]

A friend bought a new Shield of some variety and had a heck of a time getting the magazine to full capacity. After a couple of range sessions that was no longer a problem.

I'm glad to hear that the Wolff springs work well because at this point I'm likely going to have to go with them. I might give S&W customer service a call and see if they are still stocking OEM springs. If not, I'll order some Wolff springs.

Springs and their service life get discussed fairly often. From what I have read from people who seem to be in the know, is that properly made and tempered springs "break in" a little when first put into service, and after that it is the number of compress and release cycles that determines service life. Not from leaving magazines loaded for a long time for example.

I can attest to that fact that new springs do need to be "broken in". For example, my Kahr K9 magazines have very stiff springs. They were very difficult to load the first 6 or 8 times, I even resorted to using a loading tool. Now they are still stiff but I can load them completely without undue stress to my thumb. Same deal with fitting a new recoil spring to a 1911 type pistol for example.

All of that said, I have all new Wolff springs in my Model 1006 including their extra power magazine springs and I have encountered no problems what so ever. I also have Wolff extra power magazine springs in my pre-Model B CZ-75 and they too are not a problem. Other than being pretty stiff to load.

I would go ahead and change out all the springs on your Model 6906 and fire a few magazines full just to verify functionality. I think you'll be just fine.

 

[stansdds]

I've used Wolff +10% magazine springs. They are a little stiffer than factory springs, but work just as well. I can still stuff all 12 rounds into my Model 6946 mags and a full mag seats just fine in the pistol with the slide forward.

 

[GaryS]

Perfect, that's all I need to know.

Thanks.

I've used Wolff +10% magazine springs. They are a little stiffer than factory springs, but work just as well. I can still stuff all 12 rounds into my Model 6946 mags and a full mag seats just fine in the pistol with the slide forward.

 

[ACEd]

At this point it's probably safe to assume that just about any 3rd Gen magazine is used.

For the magazine body, there's probably no difference in how they were stored absent being in extremely humid environments. As for the rest, I consider springs, followers, and baseplates to be items that will need periodic replacement.

Not sure I agree about cause of spring sag / creep being UNRELATED to storage (LOADED vs EMPTY) but definitely agree with everything else including springs being a maintenance item and Magazine Spring "sag" is real.

In my experience with WW2 / Korea vintage M1 Carbine mags, mags stored Loaded for Long Term definitely take more of a set vs those stored unloaded.

From an engineering standpoint, it would seem that there are 3 potential reasons for spring sag. 1. Short term Stress exceeding Yield Point of material; 2. High Cyclic Stress approaching the Yield Point; 3. Creep due to Long term High Static Stress approaching the Yield Point. Each of these would be a function of Material Choice and Load producing the Torsional Stress in the Magazine Spring Wire.

Since each of these requires High Stress relative to Material Capability, I would assume the Stress State of a Fully Loaded Magazine must be relatively high.

My M1 Carbine issue may be a choice of spring materials available in those wartime days, but personally I try to avoid long term storage of loaded magazines.

 

[Walter Rego]

There was an interesting article in Gun Digest back in 1996 by author Bob Bell. He relates how he took a USGI magazine loaded with steel case .45 ACP WWII production ball ammo, and known by himself to have remained loaded for 50 years and decided to test fire his WWII era M1911A1. It functioned 100%.

I suppose the stress on a 1911 magazine spring loaded with 7 rounds is much less than a double stack magazine loaded with 15 rounds but it made for a good story. I don't keep any hi-cap mags loaded for long periods but feel pretty confident with a couple of 7 round mags that are loaded for home defense purposes.

 

[gmborkovic]

I gather from this great discussion that all springs are not created equal.
And, if replacing springs makes sense to you, than just do it and feel comfortable and secure in your decision.

 

[ACEd]

As to 1911 mentioned above, the magazine functioned - that does not say there was no sag in the mag spring, just that the amount of sag in a 7rd mag was not enough to make a difference in 1 cycle. Was the spring checked against a new spring? Was it reloaded fired again and for how many cycles would it perform correctly? Maybe good forever or maybe not.
I agree with a previous post - I always assume a used mag should be inspected. I have found varying degrees of sag in mag springs - from no significant difference compared to new to more than an inch shorter than new (approximately 15% weaker compared to a new 8 inch long spring). If in doubt, replace spring. Same for recoil springs - I always check.

 

[4T5GUY]

I’m not questioning magazine spring “sag”. My question is how this is being measured. How is 15% weakened from new determined ?

I’ve paid attention to how people are measuring recoil spring weights but I don’t recall anything about measuring magazine spring weight.
Of course a magazine with a new spring is harder to load than an old well used one. You can feel a new spring is stiffer.

Laying magazine springs, (and recoil springs,) side by side can’t be an exact measurement.

The attached image is of two comparative NOS magazines. Neither have ever been loaded. They have the same number of coils but are not the same length.

Jim

 

[ACEd]

I’m not questioning magazine spring “sag”. My question is how this is being measured. How is 15% weakened from new determined ?

I’ve paid attention to how people are measuring recoil spring weights but I don’t recall anything about measuring magazine spring weight.
Of course a magazine with a new spring is harder to load than an old well used one. You can feel a new spring is stiffer.

Laying magazine springs, (and recoil springs,) side by side can’t be an exact measurement.

The attached image is of two comparative NOS magazines. Neither have ever been loaded. They have the same number of coils but are not the same length.

Jim

I said 1+ inch sag in a spring which was originally 8 inches uncompressed would be APPROXIMATELY 15%. That would be at full compression. I dont know of and physical measurement technique.

And of course what you are really concerned with is not the Spring Stiffness but rather the Spring Force on the topmost round which varies with the amount the spring is compressed (number of rounds inserted compared to magazine capacity)

Spring Stiffness is quantified in pounds per inch. Its a calculation thing. Spring Stiffness is determined by the Torsional Modulus combined with the diameter of the wire, the total length of the wire, along with the coil dimensions.

Since only the uncompressed length is changing - assume a 1.25 inch sag of the 8 inches (roughly 15%) is no longer providing resistance. (By the same WAG - in Engineering terms "Wild Ass Guess") 1 inch sag in 10 would be 10% - or 2 in sag in 10 would be 20%)

You could do a more precise calculation with material properties of the metal combined with exact dimensions. But in this case its just a WAG in the absence of a lot on numbers and the accompanying calculations.

But again the Spring Force on a given round would vary - the WAG would apply to a fully loaded magazine.

And in the case of the last round in the magazine, the effect of the sag would be significantly more detrimental as the compressed length (spring force) would be at its minimum - in an extreme case of spring sag the force could be Zero.