Load magazines to 80% of capacity to prevent spring fatique

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Alan Fud

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Since this applies to both pistols & rifles, I thought it should go here

Couldn't sleep the other night so I watched some shows that I recorded earlier. Must haved made a mistake on the recorded because I apparently either recorded the wrong channel or the wrong time for one of the shows and ended up recording some show on the History Channel having to do with the M16. What I did record was pretty interesting and I wish I would have caught the whole thing.

Anyway.

There was a segment with an individual who worked with "the greatest gun inventor since John Browning" and it was said that magazines should be loaded to 80% of their capacity to prevent spring fatique. It was said that troops with 20 round mags were told to load it with only 16 rounds.

While I normally download by a round, this was the first time I heard of this "80% rule". Have other members heard of this or seen the show? Does anyone else follow this 80% rule?

This would mean my Para P14.45 should be loaded with (11+1) rounds instead of the (13+1) rounds that I now keep in it. My 4013TSW should be loaded with (7+1) instead of the (8+1) that I keep in it.
 
Never heard that before. I always load my magazines to full capacity and have never had a spring fatigue problem. I believe that alot of times if you are having that problem the springs are bad to begin with. You also hear stories from time to time of downloaded dropped guns or magazines in which the rounds juggle around and stovepipe. Not good.
 
It depends on the mag. A properly designed mag takes its spring's compressability into account and allows loading to full capacity. This generally means a follower deep enough to hold the compressed (but not over-compressed) spring. There are some fairly well documented cases of 1911 mags loaded to full capacity for decades and still functioning properly.

From what I hear, it WAS common practice to download the 20 rnd M-16 mags, both to save the spring and to prevent misfeeds when fully loaded. But I also hear that the M-16 mags were considered semi-disposable.
 
From what I understand, when you store magazines full of rounds for extensive periods of time, it would be a good practice to rotate them and let the ones that were under compression for so long rest a while. While this may be a good habit, it probably isn't necessary... If you ask me, a good magazine should be able to hold a full load continuously for years with no failure, or else it's not a good magazine.

Ryan
 
I have magazines that have been loaded to capacity for years (my H&K Compact has four magazines that have been only unloaded for the length of time it took to load them again, I have had them for 6 years now).

Others have mentioned that it is the actual movement that reduces a springs capacity. So the magazine left loaded for years will actually retain its power longer than the magazine that is loaded and unloaded constantly.

C
 
Hmm... it just seems that springs tend to lose compression and elasticity when compressed or stretched for long periods of time. I guess if they're high quality they should always return to standard compression though, even after a being loaded up for a long time.
 
Agree with Standing Wolf.
I keep all mags topped off, inspect and replace springs as need.

On TFL there was a number of threads on this. Concensus - the spring doing work caused more fatigue.[ Loading / unloading ]

I have some mags, single and double been loaded for years. Have kept Shotguns loaded for years. No problem here.
 
I know of some of my fellow Marines who swear that you HAVE to load only 28 rounds into our 30 round mags, otherwise they may cause failures. Myself, I always load to full capacity, and when going to condition 1, I always replace the mag that I chambered a round from with a full mag. Never had a single problem...
 
If you are handed a worn out M16A1 or A2, with a pile of old mags that have an unknown number of rounds threw them, you may have to download the magazine because nobody bothered to chang the spring 20,000rds ago.
 
If you are handed a worn out M16A1 or A2, with a pile of old mags that have an unknown number of rounds threw them, you may have to download the magazine because nobody bothered to chang the spring 20,000rds ago.
Click to expand...

Not to mention they were built by the lowest bidder.

I always fully load my magazines, chamber a round, then top off. Never had any problems and I don't figure there's any sense going into a gunfight with less than I could reliably have.
 
The only time I've ever heard of reducing a load for long term "storage" is from Remington with respects to their extended shotgun magazine. Other than that, I've always kept my magazines fully loaded.
 
With pistols I top off so I have 10+1 on tap. With FAL's however, I only put 19 in the mag. Once every range session with full mags, the bolt will fail to go all the way into battery due to the difficulty of stripping the first round off a full twenty rounder. Downloaded to 19 it runs flawlessly. Fatigue? Never been a concern of mine.

atek3
 
Springs wear from repeated compression and decompression, not from being compressed for a long period of time. Once a magazine is loaded to capacity for a second, it may as well be loaded for a year or ten, from a metallurgical standpoint.

I load my mags to full capacity, keep the carry mags loaded all the time, and invest $16 into a set of new +5% springs from Wolff every two years or so.
 
I cant recall how much they are, but IMO, magsprings are cheap. If it holds 7, 8, 14, or 17 rounds, thats how many I'm putting in.

The only thing I download is my Thompson mags. I probably wouldnt if they made 30 or 60 round boxes. That will probably change when I start reloading though (partial boxes get on my nerves for some reason I cant explain because I dont get it myself).
 
A liitle side trip here. I've built A LOT of engines over the years. I've never yet loosened rocker arms on an engine to decompress valve springs for storage. Never had problems. But on an engine we ran at 8,000 rpm for a 100 mile road race(love Nevada:D) those springs were done.

Our moderator has it: It is cycling springs that fatigues them. As long as it is properly designed it doesn't care which end of its range it's in.
 
The only problems that I have ever had with glocks have been two used ones that I bought at different times. Both of the previous owners had all their mags (all high caps) completely loaded to capacity for who knows how many years. I had fails to feed with both of them. I got new springs and the problems went away. No one can convince me that magazine springs don't lose their horsepower. I once heard that if you download your magazine even by 2 rounds, you decrease the "load" on that spring by 50%. Now, I believe that to a certain extent. But I am not an engineer, so I can't know if it is 100% true.
I feel more comfortable having my pistol mags downloaded by one. If others deride that practice, then so be it. I am a sum of my experiences.
john l
 
With the right material, a spring shouldn't degrade appreciably when left compressed.

There is a phenomenon called creep which would effect springs that are loaded for prolonged periods at elevated temps that would result in the spring relaxing. Again, shouldn't be a problem with quality parts.
 
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