Thread: Keeping semi autos cocked

Originally Posted by Marty Henry

So why did my gun sergeant say ease springs or did he mean something else altogether?

'ease springs' sounds a bit dodgy, out of context.

I like to have my chamber closed onto one of those bright orange plastic thingies.

Originally Posted by carlhurley

this is crap springs wear out because of use not compression the metal only has so many times that it contracts and expands before it wears out leaving your magazine full doesnt harm it loading it and unloading does if the springs failed because of being compressed then all your cars would be sitting on their axles after a couple of years think vintage cars tappet springs etc

So you've done a bit of metallurgy and know that steel under a certain stress level does not fatigue but does above that level? Motor vehicle springs that are loaded don't sag over time? I'm with mikee, just check it is empty and close the bolt while holding the trigger to take the load off a couple of springs.

Just to stir the pot, If you store your bolt action (cock on opening types) bolts seperate, should you decock them?

Originally Posted by Chupacabra

Just to stir the pot, If you store your bolt action (cock on opening types) bolts seperate, should you decock them?

Just to stir it a little more...............................

Not something you could do it you owned a TIKKA as you would first have to FIND the bolt before you could de-cock it

Originally Posted by gundoc

No firearm should be left cocked, nor should magazines be left loaded, as this can cause the springs to take set and lose strength. With semi autos, particlularly rim fires, the cocking handle should be held back about 5 - 6 mm while you press the trigger. This will eliminate the chance of any chamber damage.

Sounds like a good idea, however some semi auto's such as my Brno 581 can't be left with the action open or can't be fired by pulling the trigger 5 - 6 mm from closing.

One spring is from a mag that's been stored loaded for the last 3.5 years, the other from a mag that's been stored empty.

Originally Posted by carlhurley

this is crap springs wear out because of use not compression the metal only has so many times that it contracts and expands before it wears out leaving your magazine full doesnt harm it loading it and unloading does if the springs failed because of being compressed then all your cars would be sitting on their axles after a couple of years think vintage cars tappet springs etc

I've heard the same from a person who knew a lot about metallurgy.

IMHO leaving them cocked does no damage, the training rifles at work are always cocked so the safety can be on, they function well. I know magazines that are always left full, for months/years on end and they still function well.

I have just been tearing a 99E down for a youg bloke as it was sometimes firing and other times not. The spring had compressed by 4.7mm, I gave it a stretch until it was just over the correct length and we now have solid primer strikes. It will probably be OK for a next year or two but then it wil need to be replaced with a factory model.

But hey, the rifle is some 50-60 years old so one must expect some wear and tear

I'm of the belief too that springs wear out due to contractions and expansions, not from staying compressed. I've owned my Remington 597 for almost 10 years now and have always stored it either with bolt locked open or bolt closed but firing pin not fired.

Have yet to notice anything wrong with it, works as good as it did the day I brought it.
Well since I put the aftermarket extractor in it, as the factory one was terrible.

Barrett Rifles Discussion Forum • View topic - Is your spring getting soft?

A while back I was engaged in the ever popular debate over whether leaving a magazine loaded for extended periods of time would cause the spring to weaken when I remembered that I work at a company packed with materials science and physics PhDs. I put it to one of them for the final word. This is what I got in return...

Warning: This is not for the faint of heart.

****,

I’d be glad to, this sort of thing is fun (it’s the essence of engineering—to put a scientific explanation on a practical problem, right?): In my humble opinion, you will never see a misfeed occur due to a magazine spring being weakened from an extended period of time of being compressed. You’ll hear a lot of arguments that say things about creep, fatigue, relaxation etc, but I don’t believe any of them (it’s not like springs need a good night’s sleep and they’re back like new—that’s just wrong). Sure: if you leave your magazine in a 700F oven all the time, the metal is going to get softer, or leave it wet or drop it in saltwater and don’t clean it right away, then the spring is going to corrode and get weaker because there’s not as much metal in the spring any more. Maybe there’s something to the idea of a magazine that’s been sitting stationary for many years (not getting jostled around) where the rounds get bound up in some way and that leads to a misfeed—but that’s not due to the spring. The spring will be just as strong as on the day it was forged.

One reason I can think of for an aging or weakening effect would be due to creep or relaxation of the spring. Creep is when metal deforms over long periods of time when subjected to a sustained force that is much less than the yield strength of the material. The argument would be that a fully loaded magazine puts the spring under constant pressure and that the spring slowly deforms over time making it weaker. I argue that only an abused or poorly designed spring would do this. In the ‘70’s, houses were wired with aluminum wires because aluminum is cheaper than copper and is almost as conductive. The problem is that aluminum has a much lower melting point than copper and is more susceptible to creep. The problem with aluminum wire comes when you tighten down lug screws on terminal blocks: stress is applied to the aluminum and over decades, the wire deforms very slowly. Since screws don’t self-tighten it’s possible to get to the point where the connection gets loose and therefore is more electrically resistive, so when the circuit is under heavy load, the connection can get hot and can cause house fires. As a result aluminum wiring is now always landed with spring-loaded connectors that can’t get loose over time. So: creep is real and well understood. Does creep apply to springs? Yes, a spring will creep too, but who is going to make a spring out of un-alloyed, annealed aluminum? Spring steel is very strong and has a very high melting point. At room temperature, creep rates are negligible (see below).

You might also hear an argument that fatigue causes springs to get weaker (ie if you load/unload your magazine often it’s better/worse for the spring). Fatigue is cyclic stress loading (like the fuselage of an airplane that’s pressurized and depressurized every time it takes off and lands). Remember, fatigue is just a dynamic creep. It’s not like letting the material rest will heal it’s fatigue. Fatigue has more to do with stress concentrations (nicks/cracks) where damage is slowly propagated through the material. You might have heard about how southwest airlines grounded a bunch of their planes recently when they had one plane develop a huge crack in the fuselage mid-flight. This is a perfect example of a well-designed material. Airplane fuselages must be very fatigue resistant so that even if a crack forms it can grow feet in length and the plane still won’t catastrophically destruct (the airplane landed safely in the SWA case). Note that the military designs aircraft much less conservatively and has to use much more expensive x-ray crack detection technology because in fighters, millimeter long cracks will catastrophically destruct. I digress... As for magazine springs, fatigue is not really an issue unless the spring has been abused/damaged (think corrosion or nicks/cuts/scratches from a bad repair). Fatigue in a spring would lead to breakage, and not so much to weakening. So fatigue won’t soften springs either.

You wanted a technical explanation, here goes: unlike what you were probably taught in high school chemistry, metals are crystals where the constituent atoms are held together in a lattice, all separated from each other by a very specific distance. When you deform metals, defects called dislocations move through the crystal. A dislocation is a line of broken bonds in a crystal. As a dislocation moves, bonds break and reform. Multitudes (thousands or millions) of dislocations moving through a crystal allow the bulk metal to change shape without the whole crystal fracturing like glass (dislocations are a primary cause of the malleability of metal—glass doesn’t have dislocations). Dislocation mobility is proportional to temperature: at low temperatures metals are more likely to break than bend and at high temperatures, metals get very soft. This is due to vibrational energy of the lattice and the probability of the atoms to stray from their normal lattice spacing (ie the stretchability of the atomic bonds). If you’re designing a spring, the last thing you want it for your spring to deform (fail), so you want to use a high melting point material that’s more likely to break than bend at room temperature. As a result, creep for springs at room temperature is very low—much lower than that of soft or pure metals (eg aluminum wire). So: as long as you have a properly designed spring that hasn’t been stored in a hot oven and hasn’t been plastically deformed, chances are that your spring is as stiff is the day it was made. The question still remains though: if all metals creep (and springs do too), then how long before the spring in a fully loaded a magazine is significantly softer? For 316 stainless steel at high temperature (~550C) you can expect a 1% plastic deformation (1% is a commonly used failure criteria) from a reasonably medium-high constant stress (160MPa) after a little over a year (actually 10,000 hours). Since the creep is exponentially dependent on temperature through an Arrhenius relationship to activation energy of the creep mechanism, at room temperature you can expect this length of time to be a factor of about 10^18 longer (that’s about 3.7 million trillion years, I think). So, I think it’s safe to say that creep isn’t softening your magazine springs.

How’s that?

Thanks,
****

If you want to doubt that, go ahead. I think I'll take his word for it.

Originally Posted by Mauser308

As far as magazines, I have a sneaky suspicion that leaving a magazine loaded for general people could get you in the crap...

You just can't store them with the gun (like ammo anyway), or transport them in motor vehicles on roads without a permit.

Originally Posted by Banana

You just can't store them with the gun (like ammo anyway), or transport them in motor vehicles on roads without a permit.

So you can get a permit to carry loaded magazines in your car with your gun??

Land Transport (Road User) Rule 2004 (SR 2004/427) (as at 01 November 2014) 7.21 Loaded firearms – New Zealand Legislation

Originally Posted by Banana

Land Transport (Road User) Rule 2004 (SR 2004/427) (as at 01 November 2014) 7.21 Loaded firearms – New Zealand Legislation

So I presume it would be for special response teams or police whom are not part of the defense force.

Not Billy Bob and his dog rusty?