Theoretically, you're doing more HARM, than good.

Springs do not wear out loaded, or unloaded, but with repeated loading and unloading, or cycling. A spring in constant compression does not soften. A spring in constant "relaxation" does not soften. But repreated compression, and release, fatigues the steel, and softens the spring.

You're better off loading the mag, and leaving it loaded!

PS An unloaded gun, in the middle of the night, is an awkward rock...

Jeff

The movement of the spring is what causes spring fatigue so I agree with JeffWard. You are doing more harm than good. Leave it loaded bro.
Scott

Jeff is on the money. You're causing the spring to fatigue. Leave it loaded. An unloaded pistol is just an expensive doorstop, anyway.

Good to know... Thanks for the help. Hopefully someone else can gain some knowledge from my lack of.

-Nate

There are no stupid questions; just stupid answers. =]

Thanks everyone... I learned something I wasn't sure about either.

As did i! Good to know thhat a loaded mag doesnt hurt the spring!

Originally Posted by JeffWard

PS An unloaded gun, in the middle of the night, is an awkward rock...

Jeff

I think its more like a boomerang that doesn't come back.

The military is recommending that the top round in the magazine be replaced occasionally - not sure of the time line - as the loading in the chamber may compress the cartridge and cause a misfeed/misfire over time.

So if you're like me I keep one in the chamber when carrying. At home I unload and rotate my rounds then.

Originally Posted by SaltyDog

The military is recommending that the top round in the magazine be replaced occasionally - not sure of the time line - as the loading in the chamber may compress the cartridge and cause a misfeed/misfire over time.

So if you're like me I keep one in the chamber when carrying. At home I unload and rotate my rounds then.

Repeatedly chambering the same round, slamming the nose of the bullet into the feed ramp, MAY if done hundreds of time, cause the bullet to be pushed deeper into the case. If the bullet is pushed deeper into the case, this can cause a LOT of pressure build-up, and worst case scenario, a "Kaboom". Not a miss-feed or miss-fire.

The realistic likelyhood of repeated chambering of a crimped, factory-loaded, conical/pointed bullet actually getting pushed back is somewhere between never and almost never.

If you have so much friction/resistance on the bullet from the feedramp as to cause bullet set-back, the LAST thing you need to worry about IS bullet set-back. You're going to have serious feeding issues first.

You can visually check your bullets for set-back, by checking OAL (Overall Length). Not a bad idea anyway for factory loads, and MANDATORY for reloads. Just place all the rounds side-by-side on a flat hard surface, and rest a straight-edge across the top. If they're all the same length, they're good to go.

I'd be more concerned with lip deformation from repeated chambering of a hollow-point round, than of bullet set-back.

my $0.02.

JeffWard

Originally Posted by JeffWard

Repeatedly chambering the same round, slamming the nose of the bullet into the feed ramp, MAY if done hundreds of time, cause the bullet to be pushed deeper into the case. If the bullet is pushed deeper into the case, this can cause a LOT of pressure build-up, and worst case scenario, a "Kaboom". Not a miss-feed or miss-fire.

That makes more sense than what I was told.

Still not a bad idea to change it every once in a while.

This is a requirement for security forces who I assume load and unload every day/shift.

I was taught in military and as LEO and in a class I took once - to "rotate" my magazines monthly.

And I used to do it - for years.

I do not believe that you need to do that anymore.

But you're sure not doing any harm by doing it.

Originally Posted by JeffWard

Springs do not wear out loaded, or unloaded, but with repeated loading and unloading, or cycling. A spring in constant compression does not soften. A spring in constant "relaxation" does not soften. But repreated compression, and release, fatigues the steel, and softens the spring..

I've heard this repeated many times, but I'm not sure I buy it. Metal fatigue occurs in a material when it is repeatedly stressed beyond a certain threshold. My (educated) guess is that a magazine spring under normal use is never stressed to that threshold. If you take a paper clip and bend it back and forth in your fingers, it won't take too many cycles before the metal fatigues and fails. I have pistols that belonged to my father that have been used since the 40's and none of the magazine springs has failed or required replacement. I'm not saying that metallurgically speaking a magazine spring is like a paperclip. What I'm saying is that if metal fatigue were an issue with mag springs you'd hear about them breaking more often.

I think that the phenomenon of a magazine spring losing tension over time, when it happens, is owing to a process unrelated to metal fatigue — probably more to do with losing temper — and that any tendency to loosen up is probably directly related to the amount of time the magazine has been loaded, and that the number of times the magazine is loaded or unloaded is irrelevant. A recoil spring is another story. I can see that under use, with varying powder loads and other conditions, it could reach the threshold where fatigue could occur.

To the OP, a new magazine spring will run you $6. On many SIG models it is recommended to change the springs every 5000 rounds. As it's a carry weapon, you may want to adhere to that schedule. I concur with others who say you should keep your mag loaded.