spring fatigue and cylinder question

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I'm familiar with spring fatigue, the issue when your spring gets "tired" from being squished on top of bullets. This will cause the gun not to feed properly. I change out mags every once and a while or will not fill the gun up all the way with ammo. I can't help but wonder, how long would it take to establish spring fatigue in a fully loaded gun. A scenario of being gone for weeks and not being able to unload or simply not unloading your gun once in a while is something that is real to gun owners. I know we are supposed to be responsible so don't just throw that sermon at me.

Finally, I saw a video on youtube that said not to "fling" your cylinder back in the gun like in the movies because that is bad for the gun, but to simply guide it in with your hand after loading. Is this true?

Thanks.

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Godscreation wrote:

I'm familiar with spring fatigue, the issue when your spring gets "tired" from being squished on top of bullets. ... I can't help but wonder, how long would it take to establish spring fatigue in a fully loaded gun. A scenario of being gone for weeks and not being able to unload or simply not unloading your gun once in a while is something that is real to gun owners. I know we are supposed to be responsible so don't just throw that sermon at me.

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OK. Responsible gun owners or responsible students of metallurgy?

I did not learn of gun-magazine-springs as a special class that generally has things like tuning-forks, poppet valve springs and reactor scram springs - oh, and bicycle spokes - that have infinite fatigue life.

If you are stressing your spring into plastic deformation then its not the same spring.

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Isn't it the feed lips of the magazine that tend to get messed up moreso than the springs? Not from just sitting there but from the weight of the rounds when the magazine getsjarred around. I know my P-Mags have a special clip that goes onto the top of them to actually put more pressure on the spring and take it off of the feed lips.

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Brass Magnet wrote:

Isn't it the feed lips of the magazine that tend to get messed up moreso than the springs? Not from just sitting there but from the weight of the rounds when the magazine getsjarred around. I know my P-Mags have a special clip that goes onto the top of them to actually put more pressure on the spring and take it off of the feed lips.

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spring steel is not quite the same thing as Ductile Material, but still, that's a good graph. I think people dont generally understand that they can not wear out a spring by loading and unloading the mag too many times. Some members on this forum have pointed that out, but still the myth persists.



Consider the valve springs in your car. If the car's engine is running at 3000 RPM the valve springs is compressed/uncompressed 25 times per second. (Valve operates at half the crankshaft rate). That's 1500 times in a minute. The valve springs last for MILLIONS of cycles.



Now, your mag spring is not a valve spring in the engine, but you're not likely to wear out the spring by loading/unloading it too many times. Also, as the graph shows, unless the spring is compressed into coil bind, just simply loading the spring will not damage/weaken it.



The hair sping in a fast train pocket watch ticks 1.000.000 times in 55 hours, 33 minutes, and 20 seconds. I have some pocket watches made before World War 1 with the original spring that still runs fine. There's no telling how many hundreds of millions of tick tocks they seen and still the spring is fine.



Bottom line: don't worry about it.

(edited to fix some of the type-o's that I always make)

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6L6GC wrote:

spring steel is not quite the same thing as Ductile Material, but still, that's a good graph. I think people dont generally understand that they can not wear out a spring by loading and unloading the mag too many times. Some members on this forum have pointed that out, but still the myth persists.

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Yeah, you're right, and I also forgot that we are really talking about compression, and not strain. So I think it would fall under bulk modulus. The compressive strength of a material will be much different than it's tensile strength most of the time.

Also, loading and unloading would be cyclic fatigue. For steel it can be near infinitebut for aluminum it's not. So depending on magazine construction it may well be the feed lips that wear out before the spring.

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I once lost a fully loaded magazine for a 659 S&W and when it was found 7 years later, the spring seamed to be as strong if not stronger than the other 4 I had since it was new. Don't worry, and don't carry a partially loaded mag, you never know when you will need the extra ammo.

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Ho ho. Age hardening?