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Author Topic: Empirical data (n = 1) on mainspring fatigue from extended time cocked  (Read 615 times))

Offline Ilimakko

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Last night, after a very heavy workday, I inadvertently left my LGV with a little-used Maccari FAC mainspring cocked for around 20 hours. Yikes!

I found the gun cocked, and quickly fired a pellet to relieve the stress. Then I took a few shots through the chrono: the previously ~19J spring barely pushed the pellets out at 15J, with a velocity drop of around 80 fps. Clearly, the spring is a goner.

Hunting, I've sometimes had my springers cocked up to four hours straight, with no apparent ill effects. I've tested this for up to an hour, and measured a slight drop of around 10 fps, with lesser quality guns than the LGV + Maccari.

Gaylord stated in his R1 book that a springer left cocked for a month still has over 90 % of its velocity left. My accidental result is quite different.

Maccari springs are very long-lived / quite low-stressed. Even with this advantage, 20 hours did the spring in. I guess it's in the realm of possibilities the spring will recouperate some, but I'm not hopeful. It's a bummer, since I was about to chrono recent mods (time for another thread) with the same mainsprings I've used all the way.

With the shipping, customs and fees, I'm looking at around 60 USD to get a new Maccari spring, plus around a month of wait time. Add to this the fact that I've spent 500 pellets to get the spring truly broken in, and you maybe can see why I don't really look at (quality) mainsprings as simple consumables.
« Last Edit: June 18, 2022, 06:03:17 AM by Ilimakko »
LGV Master Ultra .22 cal
D48 .22 cal
350 Mag .25 cal
H135 .25 cal
WFH .22 cal
Fenix 400 .22 cal
G1250 .22 cal
D25 .177 cal (c. 1960)
BSF S54 Match .177 cal (c. 1965)
E-C2 5.4 mm (c. 1920)
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Offline HectorMedina

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I am sure you feel real bad about this, but maybe you should not write-off the spring altogether.
It does seem too big a loss to be permanent or typical.

In my tests I have left guns cocked for up to 5-7 days with no real ill effects.
Yes there is a proper procedure to deal with this: IF you discover a cocked gun, do NOT fire it. Uncock it and let it rest for a week. THEN, do a couple of "almost full" cocking strokes and only after that, cock it and test it with a pellet.
You may loose some power, but not that much.

Now, in the situation you're in, I would allow the spring to rest uncompressed / untouched for a week, and then do the  two or three "exercise runs", and then test it. You may find that you have lost power, but not as much.

Please keep us posted.





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Offline lefteyeshot

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Years ago I had an old pawn shop Tech Force 89 kicked like a mule and was hard to shoot. Cocked it and left it in a closet for four months. A poor man's detune. Afterwards still kicked like a mule and hard to shoot. I don't remember now but the chrony numbers barely changed.
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Offline Yogi

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Dang, if I don;t shoot my cocked springers within 20 minutes I start panicking. :-[
My Lp-8 doesn't have that much power to begin with and I do not want to lose any.

-Y
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Offline Mark 611

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I would try shooting the gun for a while so see if the springs memory comes back! you may lose a tic of velocity but IMO the spring may lose it self up again! JMO :o
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Offline Jim-in-UK

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A decade ago, I left a slightly used mainspring coil bound for 1,000 hours, during which, it lost 2% of its free length through creep, and after which, its rate of 48.8 lbf/in was unchanged - it was not fatigued.

Restoring the lost length with preload washers restored the rifle's muzzle energy.

I'm surprised 20 hours in a rifle should have such an effect.
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Offline lefteyeshot

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(N=1). What's N?
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Offline h2rider

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N = 1 means a data set of one sample.

Offline Bayman

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This topic has been discussed several times and people's experiences range from no loss to lots of loss. I believe the differences are caused mostly by the spring design, material, how compressed it was and for how long.

My experience with racing engines and standard automotive engines is entirely different. When I was involved with racing the engines they had to be stored with the rockers removed. If it wasn't one or two valve springs would be stored fully compressed (near coil bind) and they would lose their strength. This is bad with a race engine because the affected valve springs will float prematurely leading to power loss and possibly a dropped valve (very bad).

On the other hand standard automotive engines can be left assembled almost indefinitely with no ill effects to the valve springs.

My experience with airgun springs is I left one of my Vortek kitted Hw30s cocked over a weekend. It lost about 50 fps which is about 7%. So when Tom Gaylords experiment keeping 90% sounds ok, but losing 10% is nothing to sneeze at.

Not all guns and springs will have the same if any loss because of the differences in spring design, material, how compressed it was and for how long. I would just avoid leaving a spring gun cocked for more than a few hours.

Be well
Ron


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Offline nced

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Last night, after a very heavy workday, I inadvertently left my LGV with a little-used Maccari FAC mainspring cocked for around 20 hours. Yikes!

I found the gun cocked, and quickly fired a pellet to relieve the stress. Then I took a few shots through the chrono: the previously ~19J spring barely pushed the pellets out at 15J, with a velocity drop of around 80 fps. Clearly, the spring is a goner.

Hunting, I've sometimes had my springers cocked up to four hours straight, with no apparent ill effects. I've tested this for up to an hour, and measured a slight drop of around 10 fps, with lesser quality guns than the LGV + Maccari.

Gaylord stated in his R1 book that a springer left cocked for a month still has over 90 % of its velocity left. My accidental result is quite different.

Maccari springs are very long-lived / quite low-stressed. Even with this advantage, 20 hours did the spring in. I guess it's in the realm of possibilities the spring will recouperate some, but I'm not hopeful. It's a bummer, since I was about to chrono recent mods (time for another thread) with the same mainsprings I've used all the way.

With the shipping, customs and fees, I'm looking at around 60 USD to get a new Maccari spring, plus around a month of wait time. Add to this the fact that I've spent 500 pellets to get the spring truly broken in, and you maybe can see why I don't really look at (quality) mainsprings as simple consumables.
Years ago when I lived in West Virginia I had a similar "forgot the gun was cocked" situation, however with a different outcome. At that time I was shooting .177 cal 10.5 grain boxed Crosman Premiers and was trying to get 800fps muzzle velocity using an "old design" HW piston seal (thin parachute edge). To get a velocity boost I fitted the Beeman R10 (rebadged HW85) with a heavy wire Maccari Steelgate spring (discontinued years ago) and was disappointed that the 10.5 grain pellet velocity was only 780fps using the factory HW piston seal.

After the "test session" I put the R10 away and the next day I found that the gun was put away cocked. I shot the gun and was sure that the spring was sagged after the 24+ hour  cocking and indeed the cocking effort for the next shot was easier than the previous day of shooting. A few shots over the chrony showed a velocity increase to 790fps using the sagged heavy wire spring.

That was in my "early springer years" when all I did was replace parts for "tuning" and I learned that springer velocity was more about balancing the internal components, not just adding a stronger spring. With the R10 it became obvious that the timing of the pellet "popping past the leade" with stiff spring was off, however the timing was better balanced after the Steelgate spring had "softened a bit" with the "long time cocked oversight". 

Anywhoo, when hunting squirrels at that time using a .540 ID x 33 coil x .128 wire Tarantula spring (the Tarantula, also discontinued years ago) shooting .177 cal 7.9 grain boxed Crosman Premiers. When hunting I would simply cock my R9 at the "squirrel woods" and hunt "normal style" without concern for how long the gun was cocked. LOL, I would get a shot at least every few hours or it was a VERY slow day indeed. At that time I was shooting roughly 10,000 shots per year (a 1250 count box of CPLs per month slowing for the winter months) and I would replace a broken Tarantula spring every 2-3 seasons and with the Maccari springs the velocity didn't significantly decrease.

A couple years ago, at the advice of a forum poster I took a new ARH E3650 spring and "scragged" it by setting it coil bound for 12 hours. The reasoning given was that "scragging" the spring would increase it's useful service life with minimal losss of velocity. Well, I tried this "scragging" and found that my .177 R9 velocity dropped 100fps vs my normal way of setting a spring by simply cocking and shooting the R9 a couple times. Here is a pic of an E3650 unset, set by cocking only, and after "scragging" for 12 hours...........


As a side note, for a while now I've been using a threaded rod and a couple flanged nuts to set my new springs like this but I don't compress to "coil bound" for 12 hours...........

This makes it easier to install since the set makes the spring about 3" shorter than unset plus the spring ID is a bit larger after the set making it easier to properly install a tight fitting spring guide. Also, I gave up on heavy wire springs years ago preferring .120ish wire offerings and a .177 velocity of 850ish fps...........


With the demise of my favorite dome pellet (die lot marked and dated 7.9 grain boxed Crosman Premier). I've found that the 8.64 grain .177 H&N FTT is promising so I'm using a home rolled spring kit based on this bare Vortek spring. The spring is a bit stiffer than the usual E3650 I normally use and it will drive a 8.64 grain FTT at about 860fps without excessive spacing..........
 
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Offline Frank in Fairfield

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When hunting with a powder burner, bullets or shot, I do not have around in the chamber.
DITTO for air arms.
When I load, I shoot.
When I cock a springer, I shoot.
The same technique for hunting with bow & arrow.
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Offline Petey

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Sometimes giving up a little power is a good thing .  How's your Accuracy?..................
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Offline Mark 611

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I can't believe it PETEY has posted!!!!! :o
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Offline Petey

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I can't believe it PETEY has posted!!!!! :o

lol....
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Offline gloob

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OP said he hadn't shot the rifle much since installing that spring. The initial velocity was high because the spring wasn't broken in, yet.

Personally, I don't bother even sighting in a springer until I've left the gun cocked for at least 4 hours. Ditto any kinda tuning. I have been tempted to tweak brand new springers with excessive twang, just to find that after breaking-in they are smooth as anything.
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Offline Ilimakko

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Thanks for the discussion, guys! It'll take me some time to go through it, after a good night's sleep (or three). But I will!

For now;

Four days after the accident, with the LGV + Maccari resting the whole time, I took another shot (heh) at the chrono. A ten-shot string with Exacts (LGV's favorite food) revealed that the spring had sprung back some: a whole 0.8J, or 0.6 fpe. Now the custom FAC spring makes the pellets go roughly at the OEM 12 fpe level.

Since the Maccari spring has quite a bit of buzz (being a little oversized on the OEM spring guide), while the OEM spring is a perfectly behaved 12 fpe producer, there is redundancy there that the beaten Maccari loses. It would've been very interesting and informative to see how it had worked with the mods, in full functioning mode.

As an aside, I too have left new springs cocked overnight and longer, with zero ill effects. The Maccari spring in question is not new, though, it has thrown hundreds of pellets.
LGV Master Ultra .22 cal
D48 .22 cal
350 Mag .25 cal
H135 .25 cal
WFH .22 cal
Fenix 400 .22 cal
G1250 .22 cal
D25 .177 cal (c. 1960)
BSF S54 Match .177 cal (c. 1965)
E-C2 5.4 mm (c. 1920)
FX T12 .22 cal

Offline Mark 611

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Duke, you can tighten the spring to guide fit using a plastic sleeve, it only needs to cover the bottom 3 coils of the spring and tucked under the flange washer to keep it from moving out of position! 8)
  • Indiana
In the words of my friend OC Bolding he told me if ur gonna Dance with DEVIL you got to wear the shoes!!!!! How true this is!!!!!!!!!!!!!!!
54 JUNKYARD AIRGUNS FORUM MEMBER!!!!!
When good men are silent only evil is heard!
Let he who is without SIN cast the first stone!


Beeman R1 carbine .20cal X2
HW95 .22cal
HW50 .20cal X2
HW50 .22cal
HW35 .177cal





U.K. Webley Tomahawk .22cal
Diana T06 460mag .22cal
Cometa Fenix 400 compact.22cal

Offline Ilimakko

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Thanks Mark, I have thought of various spring guide fattening tactics. Do you have any spesific plastic sleeve material in mind, to use in this case?
LGV Master Ultra .22 cal
D48 .22 cal
350 Mag .25 cal
H135 .25 cal
WFH .22 cal
Fenix 400 .22 cal
G1250 .22 cal
D25 .177 cal (c. 1960)
BSF S54 Match .177 cal (c. 1965)
E-C2 5.4 mm (c. 1920)
FX T12 .22 cal

Offline Mark 611

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Pop bottle plastic has always worked for me! ;)
  • Indiana
In the words of my friend OC Bolding he told me if ur gonna Dance with DEVIL you got to wear the shoes!!!!! How true this is!!!!!!!!!!!!!!!
54 JUNKYARD AIRGUNS FORUM MEMBER!!!!!
When good men are silent only evil is heard!
Let he who is without SIN cast the first stone!


Beeman R1 carbine .20cal X2
HW95 .22cal
HW50 .20cal X2
HW50 .22cal
HW35 .177cal





U.K. Webley Tomahawk .22cal
Diana T06 460mag .22cal
Cometa Fenix 400 compact.22cal

Offline Model25

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My good friend passed away, I got his bone stock, well-used, D52. I was having shoulder problems and struggled to cock it. I cocked it and put it away. It remained cocked for over 4 years straight.  I chronographed the rifle when I first got it.  Almost 30 years later I chrnoghraphed it again using pellets from the actual box that I used for the first test. After 30 years of moderate use, the velocity was on average 8FPS slower using the same pellets and spring. Obviously a proper spring placed in a well-engineered application.  I have had a d27 for about 39 years. No problems with leaving it cocked either. This hysteria about leaving the gun cocked is based on tribal wisdom that is not based on facts. So, I will agree to disagree.
Mike