Is it harmful to a magazine to store it full of bullets? Will it weaken the spring?
ETA: Oops, this should be in GQ. Could a mod please move it? Thanks.
Supposedly yes it will weaken the spring, and I can see how it would.
But most cops and armed couriers simply load up the gun and leave it loaded for months at a time. To be sure, I had the occasional co-worker who completely unloaded their weapon every night and loaded it up again the next day, but then it becomes a safety issue too. That person got severely reprimanded for being stupid enough to do it on the street next to their car. (What if it had accidentally discharged when you were chambering the round? That’s why we have the safety barrels in the shop, dumbass!)
For my own experience, it seems to weaken them a little bit, but heck, some of those springs were so tight in the first place that it became problematic to get the full 15 rounds in without destroying my fingers, and I welcome them being a little less stiff. Doesn’t seem to have affected their feeding.
I’ve have mags for my 9mm that have been kept loaded for 15 years. They function perfectly.
I know spring fatigue is nearly not an issue at all, but I still rotate the magazines on my 1911, so the same magazine isn’t always loaded. Only every few months, when I go shooting.
I’m no gun expert, but in the Army, we were always told to empty the magazine, count the rounds and rotate in a fresh magazine whenever we cleaned our weapons. I think the idea was more about ammo accountability and making sure the magazine was serviceable than reducing wear on the spring, but that was always mentioned in the spiel.
I know this sounds snarky, but it’s not meant to be.
How do know they function perfectly unless you empty them through the pistol? If you empty them through the pistol then the have not been loaded for 15 years.
Ok, to be very specific in my wording: For the last 15 years, I have fired my 9mm using magazines which are, at all other times, fully loaded with ammo, and whose springs, therefore, are near-continually under a state of compress.
Happy? 
The gun UL that I’ve heard is that if you leave your mags loaded, and never, ever cycle the springs, and leave them that way for years, the springs take a set and weaken, and lead to failures to feed when you do finally use them, especially on the last few rounds. Since yours do get cycled on a frequent basis, they don’t fit the UL.
I’ve also heard that cartridges can deform if kept loaded for long periods of time. I wouldn’t worry about keeping a magazine loaded if every two weeks I fired off the rounds at the range, but I definitely wouldn’t keep the same load in the gun for months.
This article claims that spring weakening is a myth, but case distortion or creasing is a real possibility so rotating/reloading magazines is good maintenance.
My S&W model 19 .357 Magnum revolver has no magazine springs…
I agree with the article… I think it’s a myth.
A side issue: I have a gun lockbox that can be bolted down or mounted so that it can’t (easily) be stolen. Where is the best room in the house to do this, and what’s the most secure way to do it?
The instructions with my gun cabinet recommended mounting it in a corner with the lock side against the wall and the hinge side opposite the corner.
That way there’s a wall interfering with attempts to pry it open.
Best room? My preference is the master bedroom to keep it out of commonly trafficked areas and where I will most likely be if I need something in a hurry.
In a closet if it’s feasable.
Sure, but you rotate the cylinder.
The US Army uses some of the cheapest magazines and weakest magazine springs imaginable. You will ruin your springs in those Circle K and Center Arms magazines if you keep them loaded for a lengthy period. Better to empty your rounds, clean the mags and stretch out the springs offen.
… or better yet, buy some factory mags or quality after markets.
The Navy isn’t in the habit of issuing small arms to everybody. Generally only the people involved in a weapons handling rate are allowed to do anything with the guns other than carry them around while on watch. The only time the gun comes out of the holster is to perform actions during a supervised gun turnover in accordance with a step-by-step procedure.
By procedure, this results in the same rounds being loaded, fed, extracted, lathered, rinsed, repeat several times a day for weeks. The brass on that top round ended up being chewed to hell after a while. I made a habit of inserting a different magazine during turnover than the one I removed just to try to spread the wear and tear across a few more rounds.
My observations on the spring issue:
Brand new magazines do have noticeably stiffer springs than magazines that have been in service for a while. However, they’re usually too stiff for comfort (it’s often difficult to load the last round or two). After a break-in period they soften up and they’re fine. And the key point is that a newish magazine after break-in is not much different than a magazine that’s been around for years.
Over time the spring weakens, but this is due to the loss of flexibility from repeated compression and work hardening. In theory, a spring subject to vibration under compression will fail sooner than without load (e.g., a loaded magazine kept in a car), but I doubt that effect is significant enough to worry about for the conditions of a magazine spring.
The work hardening issue would recommend strongly against handling the gun in such a way that the last few rounds are loaded and unloaded repeatedly, as it would harden the spring in a compressed state (See: USN small arms procedures).
It’s mostly an urban legand anyway. It is true that there were a rash of government issue 1911 magazines that suffered spring weakening (“Rule #32: Never forget that your weapon is made by the lowest bidder,”) and spring failures are not infrequently found in relic or cheaply manufactured weapons, but properly heat treated springs shouldn’t take a set, shouldn’t suffer from low cycle fatique, and will never see enough cycles in their lifetime–even with active use–to suffer high cycle fatique.
My biggest suprise is that silenus has a 9mm. I took him to be a .44 Spl/.45 ACP/10mm Auto kind of chap. Maybe a .40 S&W or a .41 Rem Mag, but a 9mm? Seriously? I mean, was it a gift from your mother, or…?
Stranger