Plunger Spring fix caused a new problem

Discussion in 'Maintenance / Tweaks / Technical Difficulties / So' started by Dag, May 11, 2007.

  1. Dag

    Dag Guest

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    Well, I just installed the plunger spring fix and made it to the range, and didn't have any extraction or ejection problems (no head bonkers). Yea! :) Unfortunately, I had several Fail To Fire, with off-center primer hits! Boo!!! :cry: A couple were so far off center that the dimple was almost into the groove at the extreme edge of the primer. I was using all nickle plated cases, but when I switched to brass cases, the problem went away. Weird! My suspicion is that I now have TOO MUCH tension on the extractor, and the rim of the cartridge is having problems fully sliding up into the extractor. Because the case is being tightly held due to the overly stiff extractor, and slightly off center, it's preventing the slide from going FULLY into battery. Probably just close enough into battery to allow the striker to release, but out of battery enough to allow the case to be slightly canted. I'm going to clip a couple more coils off the plunger spring, and try again. #^%$$#!%%^&%^!!!! If you have any other theories about what's going on, I'd like to hear your thoughts. Thanks!

    Dag
     
  2. bigtaco

    bigtaco Active Member

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    i don't think your overly stiff extractor is causing this off-center primer hit problem. when i was a noob to steyrs, my extractor was essentially stuck rock solid in its bore. and there were no FTF issues.

    you mentioned that the problem went away when you switched to brass cases but more importantly... did the problem go away when you removed the plunger spring? that would have been the variable to test out.

    were they reloads? any chance that the primers in the nickle cases weren't all 100% seated? when they were resized, maybe they're a little big? if they came out of a gun with an unsupported chamber, maybe they have a bulge in them that hasn't totally been resized by the die.

    i don't know!! i'm just throwing things out.

    to really test this, grab factory ammo and try 50 with the plunger spring and 50 without.
     

  3. Dag

    Dag Guest

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    Plunger Spring fix

    Hi bigtaco;

    Thanks for the comments. I haven't yet tried removing the plunger spring. I've clipped off two coils, and will try again Friday afternoon. Sorry, I should have said, but yes they're reloads, using hard cast bullets and mixed range brass. Two different loads, one with TiteGroup and one with Herco. I've had very good luck previously, with both loads. I'm always careful to make sure the primers are fully seated, so I don't think that's the problem. It would also seem that if they had a bulge from being shot in an unsupported chamber, they'd have problems chambering when I tried to fire them a second time. None did, and all fired on the second attempt. I like your idea of trying factory ammo with/without the plunger spring. That's something I can easily do next time I shoot (this Friday).

    Out of curiosity, what caused you extractor to get completely stuck?

    FYI, MrApathy has responded to this same post on the M&S forum. I'll be more careful next time around, so I don't duplicate posts. Thanks for your help. :D

    Dag
     
  4. bigtaco

    bigtaco Active Member

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    4 years sitting on a shelf at zander's/GSI. caked on cosmoline type stuff.
     
  5. Dag

    Dag Guest

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    Stuck extractor

    Ouch! Yeah, I guess that would do it! Just curious. Thanks.

    Dag
     
  6. Dag

    Dag Guest

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    ... and the saga continues.

    I clipped two coils off the plunger spring, and put another 150 rounds of reloads (100 rounds were nickle plate) through the gun. I have about 700 rounds total fired. I only had one FTF (fail to fire). Last time there were 2-3 per box of 50. Again go extraction or ejection problems. I'm going to clip one more coil off, and I should be in good shape. If that doesn't fix it, then it's probably time to let SAI take a look. So just be aware, if you do the plunger spring fix, you may still need to "tweak" a little to get it right.

    Dag
     
  7. bigtaco

    bigtaco Active Member

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    but i thought that the gun functioned fine without the plunger spring. ???

    as i recall, your only concern was that the empty would occasionally bonk you in the head.

    it's been known that steyrs like hot ammo. wwb and blaser are pretty hot for target loads and the defensive loads are all moving pretty nice.

    i'm just not sure that you'll get anything better or different if you send it to sai.

    and i suspect that factory ammo might work flawlessly.
     
  8. Wulf

    Wulf Premium Member

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    Dayam Dag!!! :shock:

    If ya clip anymore coils off that plunger spring, you won't have one at all! :shock: Post a pic of your plunger spring fix assembly before reassembly. I gotta see this! You may be on to something with the plunger spring fix coil cuttin' thang, but I doubt it. <shrug> Good luck!

    Wulf
     
  9. Dag

    Dag Guest

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    Weak ejection and the plunger spring fix

    Hi bigtaco - I guess it depends on how you define "functioned fine". I've never had any problems with feeding or extraction, with Wolff, handloads, range ammo, Blazer, WWB or any of several hot defense rounds. Up until the installation of the plunger spring, I had never had a fail to fire. I did experience "weak ejection", ie: brass ejecting straight up and landing on my head, or ejecting straight back into my face, and to me, that's not "functioning fine". That's a malfunction. I think West01 said that if I end up in a firefight, hot brass in the face is the last thing I should worry about. I disagree! :!: What happens if that hot brass just happens to hit me in the eye? What happens if that hot brass hits me in the face, just as the a second BG is starting to engage me? I'm sorry, but I can't have my primary defense gun trying to distract me like that. I've made some good progress, and I have high hopes that my next range session will be completely free of both Fail to Fire malfunctions, and hot brass in the face. If I can't reach that state with my M40-A1, I won't use it for personal defense. I do still need to do some more testing with with my defense ammo (Gold Dot and Golden Saber currently, likely CorBon DPX later), because if the gun "behaves itself " with those rounds, I can live with the occasional "head bonker" with practice ammo. Just FYI, my handloads tend to be close (but not above) SAAMI maximum. I don't shoot "wimp loads".

    Hi Wulf - When I put it together, after clipping that one last coil, it's still pretty stiff, so I think I'm still getting some boost from the plunger spring. The only reason I started clipping coils, was because of the Fail to Fire malfunctions I started having, when I first installed the extra spring. Bear in mind that my first plunger spring installation was REALLY tight (and caused multiple Fail to Fires per 10 round mag - yeah, "Calif Hi Cap" :cry: ). I'll post some photos (I finally figured out how :) ) when I get home tonight.

    Thanks all for the input. Good Stuff! :) :) :)

    Dag
     
  10. Syntax360

    Syntax360 Premium Member

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    Re: Weak ejection and the plunger spring fix

    [quote="Dag"What happens if that hot brass just happens to hit me in the eye? What happens if that hot brass hits me in the face, just as the a second BG is starting to engage me?[/quote]

    Your eye will blink and the case will bounce off your eyelid and you will hardly notice. Maybe... just maybe... you will notice a slight sun-burn sensation on your eyelid after the fact, but I'm pretty sure you would be more concerned with the police questioning, etc.

    If you are wearing safety glasses, however, and a piece of brass gets stuck pressed against your closed eyelid - that hurts and is a distraction. :shock: But don't worry - the pain will subside in a few hours. :)

    I would definitely be more concerned about FTEs and FTFs than brass bonking me in the head - epsecially since most users report the brass problem going away after a short breakin period, but maybe that's just me. :?
     
  11. Dag

    Dag Guest

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    Hot Flying Brass

    Hi Syntax360 - Never having been in that situation, all I can do is go by what I've read, and yeah, when the fit hits the shan :) , I'll probably focus to the exclusion of just about everything else, including Hot Flying Brass. However, in the mean time, as long as I have something else to try, I'm going to keep tinkering with it. If I run out of things to try, well, I guess that's when I'll have to decide whether or not to make it my "go-to gun". After all, it feeds everything I give it, it feels better in my hand than any other gun I own and I love them sights! :D

    Thanks!

    Dag
     
  12. Dag

    Dag Guest

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    Plunger Spring Photo

    Hi Wulf

    As promised, here's the photo of what I currently have. The plunger spring is now just under 0.4", but I haven't had a chance yet to try it out. Friday afternoon. The extractor is still fairly stiff, but moveable (really uncomfortable to make it move with my bare finger). Since clipping the first two coils off reduced the number of FTFs from a bunch, down to one, I think I'm on the right track. I'll let you know how it goes Friday.

    Let me know what you think. Thanks!

    BTW, I can't see bigtaco's avatar.

    Dag

    [​IMG]
     
  13. babj615

    babj615 Premium Member

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    Re: Plunger Spring Photo

    ... I assume you understand that by removing coils from the spring, you are increasing the spring pressure?

    So, if you are having less FTF's now, with less coils, perhaps the extractor spring is too soft/weak to begin?

    :?: :? :?:
     
  14. Dag

    Dag Guest

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    spring tension

    Hi babj615

    Uh ... perhaps I missed something. So you're saying that clipping coils off a spring, which makes it shorter, increases the tension? :shock: Taking that to a logical extreme, as the spring gets down to only one coil, it's at the highest possible tension? The plunger spring is a booster spring and adds to the pressure. The extractor pin now has to compress two springs, not just one. This takes more pressure. The longer the plunger spring is, the more pressure it asserts, assuming it's no too long to fit into the spring channel. Sound right? Thanks.

    Dag
     
  15. Dag

    Dag Guest

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    Plunger Spring tension

    Hi babj615

    It occurred to me that what you're saying is true, for springs that are being stretched, but not for springs being compressed. The extractor spring is being compressed. fewer coils = less tension

    Dag
     
  16. babj615

    babj615 Premium Member

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    Re: spring tension

    YES!!!

    Simple Physics

    Don't take my word for it....

    Look here for the answer....

    Plug different values into the "Number of Coils" variable, and re calculate, paying attention to which way "Spring Constant" changes.....

    Start with a high number for simplicity... say 10 or 15 coils.... then try 8 coils, 5 coils.... etc...

    I started with a hypothetical spring 2 inches long with 10 coils per inch [total 20 coils] resulting in a 1.04 lbf/in Spring Constant.

    Clipping 4 coils [20%] from the spring changes length to 1.6 inches, and coil count to 16, resulting in a 1.30 lbf/in Spring Constant.

    So, Clipping coils [thereby reducing spring length] DOES in fact INCREASE spring pressure.

    Take any given spring, and the pressure required to compress said spring will always increase as you remove coils.

    Exactly.

    Wrong.

    Use the link above again and double the "Free Length of Spring" data box. Now double the"Number of Coils" data box as well, as the same spring twice the length would have twice the coils...

    What happened to the Spring Pressure?

    :wink:


    ...enjoy
     
  17. bigtaco

    bigtaco Active Member

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    first of all dag. i do wish you luck in finding the perfect ejection. i see you're point about brass in the face being a nuisance. i obviously didn't know anything about your reloads until you told me. so, if they're hot... your steyr should like them. try some carry loads. maybe they'll work perfect.

    as fas as the spring rate, pressure, preload and length...

    well... you're both kinda right.

    but neither of you are considering the range of motion.

    if all things remain constant, clipping coils will increase the spring RATE. ie... if one spring is down a coupls of coils, the force required to compress the spring is higher.

    let's use inch pounds. if you have a 10lb-in spring with 20 coils, it will take 10 pounds to compress that spring one inch. and the force will be spread over 20 coils.

    if we cut 2 coils off and compress the spring one inch, the force required to compress the spring is now exerted over 18 coils. consequently, those 18 coils must deform/compress more to allow one inch of compression. this is why the spring RATE is increased.

    however, the reason that this truth remains somewhat obscured to the casual observer is because springs aren't normally compressed from their free length. most springs are slightly compressed before their range of motion even begins.

    this is called preload.

    if you have a 10 lb-in spring under 15% preload and you clip two coils... you've done two things.

    1) you've inarguably increased the spring rate.

    2) you've inarguably decreased preload. this because whatever device has established the preload has stayed the same, yet our spring has become shorter.

    without measuring and calculating all the known variables, it could in fact be very possible that one could clip two coils off of a spring and between increasing the spring rate and decreasing the spring preload...

    actually produce a net decrease in spring PRESSURE seen by whatever the spring is acting on or against.

    so let's speculate that in cutting your two coils you increase the spring rate 7% but decrease the preload 10%. net effect? less force exerted by the spring. but for all of the coils we cut, we only lost 3%. purely hypothetical numbers.

    that's why it's always nice to know original spring rate along with measurements for static length, preloaded length and max compressed length and running some calculations based on what you're trying to achieve before whacking up a spring.

    in this case dag, i'm guessing that the amount you're raising the spring rate is quickly being canceled out by the decrease in preload which is why you feel less pressure on your finger. if you cut the spring down to a length at which there is no preload on the spring when installed, at this point making it any shorter will only make it stiffer but...

    considering that this spring has now become a helper spring ( the extractor spring, it's rate and preload or constant. but the plunger spring is no longer engaged when the assembly is at rest.) and is only engaged when the extractor pin is compressed enough to compress this secondary spring, this may be the perfect solution. it will be loose enough to flex, allowing the case to clear the port. but when the ejector is trying to bump the case out, the extractor will be a little stiffer, enabling it to hang on a little bit longer and clear the case to the right instead of straight up.

    good luck. do you know if you can get plunger springs in different rates? because a plunger spring with a lower spring rate might hold the answer.

    in any event... many steyroids comment on this issue. and your tinkering and process may net out a perfect drop in solution that i'm sure many users would like to try out. so keep up the pursuit and let us know what you find.
     
  18. Dag

    Dag Guest

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    Plunger Spring Tension

    Hi babj615 and bigtaco

    This has been a learning experience. :) ... which is exactly why I joined Steyr Club!

    babj615 - The spring characteristics calculator shows some really interesting, non-intuitive things. I'm going to have to play around with that some more. I probably knew some of this when I was in school (which was a long time ago), but after graduating you don't use the stuff you learned outside your major, and quickly forget it. :oops: Thanks for the link.

    bigtaco - Great response! :) Yup, I wasn't thinking about either preload or range of motion, but I'll keep playing around with it. The good thing is that I know it's possible to have reliable ejection, because so many others don't have a problem. So it's just a matter of tweaking things until it ejects reliably. As for plunger springs of different rates, this one is part of a kit, and I don't have any idea what it's rate might be. I do know that there is a HUGE variety of spring sizes and rates available, and someone that knew their stuff could probably find a replacement extractor spring that would work reliably without the need for a helper spring. Although, if that really is the case, one has to wonder why Steyr hasn't already done it! :?: :!:

    Anyway, thanks again to both of you!

    Dag
     
  19. babj615

    babj615 Premium Member

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    Dag,

    I was not taking into account any pre-loading of the spring either.

    The formula gets more complicated for that!

    I guess I am very lucky to own 4 Steyr pistols with no malfunctions to date.

    However, enough people seem to have the ejection problems that it interests me as it is a condition I may encounter in the future.

    I almost WISH I had a malfunctioning Steyr here so I could try to 'diagnose' this problem myself....

    Keep us posted, as we all want to know what your results are and how you get there!

    Cheers!
     
  20. West01

    West01 New Member

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    Hi Dag,

    First I would like to say .....very cool posts BigT and BabJ :D

    If you don't mind I'll offer a more intuitive reasoning about the spring thingy.

    But first, a material science concept; material memory. I you take a steel bar and attached it to a rigid point on one end. Then you applied a force on the other end and try bend the bar. If you stay within the elastic property of the material (Young Modulus and all..) and manage to bend it and then release the force. The bar will come back to its original shape and position. The crystalline atomic structure of metal is very strong and just likes to stay the way it is ....simple enough.. :D

    Now if you take a steel cylinder. Hey! 0.5" diameter by 2 feet long for the sake of conversation. You anchor one end to a rigid point and put a lever on the other end. The lever is installed in way that you can twist the cylinder. The cylinder is now a basic spring...a torsion bar to be more exact.

    You turn (applied force) the lever 10 deg. (of arc) for example and twist the cylinder. And then you release the lever. The cylinder will come back to it original position. These strong steel molecules just want to stay in the same place.

    Now you cut the cylinder in half, to 1 foot long and rig it the same way as before. How much force will it take this time to twist the cylinder 10 deg.. Simple....approx. two time the force. Because you are asking these same molecule to move twice the distance and since they don't like to move, they will give twice the hard time.

    And now you take that cylinder example and twist it in a spiral... you have a coil spring. Finally when you are cutting the turn on your coil spring, you are basically cutting the length of the cylinder. Thus more force is required for the same motion......

    Hope this makes smile.

    :D


    Cheers!

    West01

    :D