Load them up because they aint going to do you any good unloaded

Spot on! Storing a spring in a compressed state will not harm the spring in any way (unless it's at incredible elevated temps). It is the cycling of the spring that wears it out. Eventually it will form micro cracks, which will eventually lead to the spring breaking.

No harm whatsoever to the spring from storing your mags loaded. And I do mean fully loaded. A properly designed mag does not need to be downloaded to 28 or 29 rounds. If it was designed to hold 30 load it up and forget about it.

I don't think anyone said loaded vs unloaded is the same. I will state this one more time so it is perfectly clear, storing a mag FULLY loaded will not harm the spring. It will not wear the spring out. It will not weaken the spring over time. If a mag is loaded to 30 rounds and stored that way for 10 years that spring will be just as strong and good as a spring in a mag that was stored empty.

This is not theory, it's science. As long as the spring is not compressed beyond its yield point it will not be affected, not even a little bit.

Springs wear out and weaken over time when they are CYCLED, not when sitting. Doesn't matter if it's compressed or uncompressed.

If there were any truth to the need to down load those old mags it was because they were poorly designed and over compressed the spring when fully loaded. That is an entirely different problem all together.

Alright, lets get technical with this discussion. First lets talk about the spring taking a "set". All springs will take a "set" after a number of cycles, or from being compressed for some time. This is commonly know and the amount of "set" varies based on several factors like spring material, shaped, and processing. That is not damaging or hurting the spring, it's just part of their normal life cycle.

Second, there are a few things that will change/affect the life of your spring. The first, and easiest to see and reproduce, is deforming the spring beyond it's intended yield point. Once this happens, the spring will be mis-shapen and never be the same again. It only takes one time doing this, once it yields, the damage is done.

Cycling, as we all know, cycling the spring (usually thousands of times) will wear the spring out and weaken it over time, until it eventually breaks. As springs cycle, the metal forms microscopic cracks. Over time they get worse and worse. You can not see these with your naked eye, but they are there. This is why most springs fail from old age. Simple use and they wear out.

What you were referring to in your post is know as creep. This phenomena happens in metals as well as plastics. Although most people only think of creep as a plastic problem because most metals creep so little it's never an issue in most applications. That said, there are 2 factors that affect creep, stress applied and heat. Raise either the stress, or heat, or both and the rate of creep goes up. On a very basic level, creep is where the actual molecules of the material begin to rearrange themselves. This happens because at the atomic level, there is a good amount of empty space for things to move around. When the forces of stress and heat are applied, the molecules of start to come "unraveled" and then begin to move. This movement is very similar to what happens when the material is melted, it can then flow almost like a liquid. Although creep is usually a very slow process.

Now that we know what creep is, and what affects it, lets talk about creep in steel. Good spring steels are not very brittle and don't easily yield, that what makes them good for spring applications. Steel also melts at a very high temperature (compared to ambient temps). The closer to a material gets to it's melt temps, the worse the creep will be. This is the main reason that when stored at room temp 73F, the steel in your spring is not going to creep very much. in fact you won't be able to measure it. That is why is most low temp applications engineers don't even need to worry about creep in their steel springs.

Lets take a look at some numbers. Most creep tests are performed for a set time, usually either 10,000 or 100,000 hours. The labs will vary the stress (psi) applied to the steel, and they will vary the temps to see how the material performs. Many tests with steel start at 10,000psi and the amount of creep at that low stress for steel is extremely small.

So how much stress does the spring of an AR mag see when compressed? 1000psi? not even close. So based on scientific data from actual lab tests of steels we know that at room temp, 73F, at a stress level far lower than1000psi you are not going to see any measurable creep in steel.

As far as that test you linked to, that was pretty cool, but the one problem that caught my attention immediately was how mis-shapen the spring was while he had it fully compressed. That spring was most likely deformed beyond it's yield point. As can be seen when he sits it on the table. Notice how twisted the spring looks compared to the other spring. It shouldn't look like that. It was damaged, and that damage wasn't from time, it was from being too distorted.

Here I will show you what our spring looks like in a fully loaded mag....



Notice how nicely the spring holds its form because of our spring guide at the bottom. It looks almost perfect, not twisting or slinking going on that could damage the spring. Take a look at the spring compressed on that test page you linked to, it doesn't look like this at all.

Now, here is one more picture of 2 of our springs that I just took. One is from a brand new, never used mag. The other is from a mag that has been sitting in storage for almost a year now to test creep for our housing feedlips. Notice there is literally no visible difference in the 2 springs. Not even a little bit.



That is a perfectly good test in a real mag for an entire year, fully loaded. No change in the spring whatsoever.

So while I will agree with you that there is more stress on a spring in a fully loaded mag, you are talking about the difference of 2 stress levels that are so low they are insignificant with regards to creep in steel. And that is why it doesn't matter to the spring if the mag is fully loaded, or empty, It would be like you have hair on your arms, or no hair. They weight of those hairs are not going to affect your arm in any way.

There is not doubt more factors to consider when we open the conversation to all mags in all makes. The most important questions are what kind of spring steel was used. And was it designed properly to allow the mag to be fully loaded without damaging the spring. If all of these things are not done correctly the spring will get weak and be damaged. I know some LE who have had glock mags loaded for almost 20 years and never changed the spring. Still runs with no problems.

No worries, I totally understand. I like debating these things also. It give all of us a chance to learn.