How long can you keep magazine springs under tension?

[Jlr2267]

Time for me to jump back in. Permanent deformation at room temperature by stress relaxation in springs has been addressed in academic literature since at least the 1970's. This mechanism is completely different from both fatigue and creep. You are correct that creep is not operatimg in any significant capacity at spring operating temperatures, but relaxation does occur - I have made posts in similar threads to this effect with references to papers showing effects.

One such thread.

In short, permanent deformation does occur in springs under constant load at room temperature. The extent of this deformation depends on alloy, stress, temperature, and time. For most good magazine springs, the effect is minimal. However, there are plenty of users reporting weakened springs which may have used less-than-optimal design or materials.

Thanks for taking time to share this. Your last post in the linked thread is excellent..!!

 

[Walt Sherrill]

Great contribution to the ongoing topic of interest.

(I don't know how I MISSED that earlier discussion, as that topic seems to call out to me.)

 

[danez71]

That was a great post... and was one I saw but didn't comment on because 1) I agreed and really couldn't add value & 2) he was getting past my comfort zone in terms of knowledge.

Just to be more clear... I've never needed to change a mag spring including my 21yr old BHP. But my most compact pistol is a M&P 9c. Not very compact compared to some.

My only dog in these debates is that it is doing zero good to say that all mags can be fully loaded with no I'll effects.

That's what people ask. They don't ask about creep or viscoelastic properties etc.

The right answer is " Depends on the mag... oh you have xyz?.... that's a service weapon and haven't seen reports of problems or.... oh.. you have a R9.... recoil sings are rated for about 250 rounds (was 500 btw) and there been reports of weakening mag spring"

That how we can provide meaning answers.

There are some really really smart people in this thread and I'm glad I'm here to learn from them and hopefully share some of my knowledge.

 

[Walt Sherrill]

Rohrbaugh states that the spring should be replaced every 250 cycles? Do they make any mention of how LONG you can leave a magazine loaded before replacing the spring?

I think the Rohrbaugh mag would be a perfect garage experiment to see how leaving a "sacrificial spring" loaded affects its performance.

It would be pretty lame if a Rohrbaugh could only be loaded for, say, 7 days at a time, lol. So to me, it seems like the R9 example is supporting what Jlr2267 has been saying all along. Replace after # cycles, not amount of time.It would be pretty lame if a Rohrbaugh could only be loaded for, say, 7 days at a time, lol. So to me, it seems like the R9 example is supporting what Jlr2267 has been saying all along.

I don't see the connection. Nobody mentioned Rohrbaugh mag springs, mag spring failures, or a change to Rohrbaugh-recommended mag spring usage practices. (As someone else mentioned in this discussion, single-stack mags seem to be slightly less hard on mag springs than double-stack mags.)

After the R9 service life guideline change, I talked with a couple of R9 owners who say they have gotten more than 250 rounds out of their springs -- by using these higher-count springs at the range when they practice. They also keep fresher springs in the gun when carried. No high round counts, yet, because none of them seem to want to practice a lot -- the R9 seems to be a bit like the Kel-Tec P40 in that it's not a pleasant gun to shoot.

UPDATE: I was curious about the magazine issue and downloaded the Rohrbaugh R9 Owners Manual. The recoil spring service life is 200 rounds. (I don't know whether I heard/read it wrong, earlier, or whether it's been lowered again...)

The owner's manual does not provide any guidelines for magazine usage or suggest how often the mag springs should be replaced.

 

[danez71]

^^^^^^

I'm sure I remember it was 500 and then 250. In fact, I found a thread here from back in 2013 that mentions 250.

That's got to be because the spring is getting compressed too far. It gets pretty warm in there too.


For ex: The R9 has a 5.2 OAL and the M&P9c has a 6.7 OAL. They both 'look' to have about the same amount of distance added by the short beavertail past the slide.

So roughly speaking, the slide/spring assembly is about 1.5" shorter on the R9 but they both have to open roughly the same amount to eject the shell.

Something's gotta give... and apparently its the recoil spring in the range of 200-500 rounds.

 

[jamesinalaska]

Thank You Schwing and ku4hk

Thank you Schwing, ku4hk, and MICHAEL T.


Your responses to this question are short, direct, and memorable. And nobody can say, "Well that just isn't so."

An experiment. A magazine loaded for 20 years and still working. It answers a lot of my questions.

I like this forum because I can get good, solid answers, like yours, to good questions like the O.P.'s.