High Cap Magazine Durability

This question comes up regularly, but nobody bothers to do a search. (Or they do the search, and the search function doens't do IT'S job properly...) The topic is well researched and there is a lot of internet sources available. Here's a repeat of stuff posted in earlier discussions. It starts with a quote from another shooter, repeating a point made above. Everything BELOW the embedded quote, immediately following, has been posted here before. If you follow the link included, you'll find a lot of technical evidence, provided by others, that supports the points made. Magazine springs wear out from the action of compression and decompression (loaded and emptied, loaded and emptied) over and over many hundreds or thousands of times, not from being left loaded. That's partly correct and partly incorrect -- using/working the springs MIGHT cause some damage over time, but in most cases, the springs have been designed to work within a range of motion, and there's enough reserve built in that it doesn't matter. (How often, over the years, have you heard about tappet springs in cars having to be replaced -- even though those springs may have cycled millions of times in a given car?)

Spring deterioration from long-term (loaded) storage while compressed is likely to be a problem ONLY with hi-cap mags used in full-size guns, or mags in compacts or sub-compacts that hold almost as many rounds as the full-size models. Some 1911s 7-round mags from WWII, kept loaded for 50 years, still work beautifully; other mags in some sub-compacts don't last long at all if you keep them loaded. Compressions or cycles alone aren't necessarily a spring killer. It all depends on the spring and how it's used.

I have had a bunch of CZs, over the years. Note: the 10-round, 15-round, 16-round, 17-18 round after-market mags used with those guns all use the same springs. Which springs, do you think, are working harder as they do their job? Do you think the spring that has lifted 17 or 18 rounds from it's compressed to uncompressed state has done the same work as that same spring in 10-round mag? Just one spring compression in both examples but a lot different work was done -- roughly 70%-80% more work, in one sense, and it's also been compressed more completely, as well.

As noted above, what the spring does (and how it does it) is as important as how often it does it. A fully-loaded mag is a working mag: it's trying to lift those rounds up the whole time it's stored away. If those springs are near their design limits, that will eventually cause some deterioration; if they're NOT near their limits, there's generally enough "reserve" left that it likely will not (ever) matter. That's why Wolff Springs recommends downloading a round or two for long-term storage of some (hi-cap and compact) loaded mags.

The life of the spring depends on what it's designed to doand how it's use pushes the spring toward the limits of that design envelope. (Spring designers talk about "elastic limits.")

Here's a link, below, to an pretty comprehensive earlier discussion, which contains links to various technical sites on the Web. It's one of many such discussions we've had here, but one of the most recent ones. One of the responders is an engineer who has taken an interest in the topic and did a lot of the research cited. Look for danez71's response.

There's a lot of bad info out there, most of it based on personal experience with one type of gun -- the experience was true for that (or those) guns, but may not be true for many other guns. Hi-cap and sub-compact mags seem to be where the biggest problems occur.

Be sure to read ALL the way through the message chain.

http://thefiringline.com/forums/showthread.php?t=521717

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Last edited by Walt Sherrill; Today at 06:37 PM.

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