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Page AR-15 » AR Discussions
AR Sponsor: bravocompany
Posted: 12/21/2008 7:17:02 AM EDT
So I was having some issues on my 6920 b/c of a weak buffer spring.  I was a bit disappointed that my buffer spring only lasted 1500 or so rounds, so I wanted to get a much better spring.  I ordered the chrome silicon spring b/c I thought I'd never have to replace it.  

My first outing with the new spring was yesterday, and. . . I need to replace it.  

I got several rounds pinched by the bolt on the way into the chamber, and the bolt would not lock open after the last round.  

I swapped springs and buffers with a friend's rifle (non-H buffer), and everything was perfect.   The spring says for carbine length guns, so I'm not sure why this spring is causing these malfunctions.  Any ideas or recommendations?  

Thanks!
Link Posted: 12/21/2008 7:44:33 AM EDT
[#1]
What makes you think that the spring was the problem in the first place
Link Posted: 12/21/2008 8:02:37 AM EDT
[#2]
Quoted:
What makes you think that the spring was the problem in the first place


+1

Consider your gas system.
Link Posted: 12/21/2008 8:06:23 AM EDT
[#3]
PM me a price, if you're considering selling it.
Link Posted: 12/21/2008 8:15:20 AM EDT
[#4]
Well b/c it just did not close with any level of authority.  At times, the bolt wouldn't fully close at all.  It just didn't have enough power to push it all the way to locked.  

Now it seems I have too much power.  Not sure it could be the gas system.  How would that cause the gun to fire the last round in the mag, and not lock the bolt open?  Then again, the spring doesn't make sense on that one either.  But I know when I change the spring to my friend's the problem does not happen.  
Link Posted: 12/21/2008 9:03:37 AM EDT
[#5]
My Back Up M4 has a VLTOR
I changed the coil spring because it was to heavy


A Quality spring should last 10,000rds even more
Link Posted: 12/21/2008 9:04:39 AM EDT
[#6]
Quoted:
Well b/c it just did not close with any level of authority.  At times, the bolt wouldn't fully close at all.  It just didn't have enough power to push it all the way to locked.  

Now it seems I have too much power.  Not sure it could be the gas system.  How would that cause the gun to fire the last round in the mag, and not lock the bolt open?  Then again, the spring doesn't make sense on that one either.  But I know when I change the spring to my friend's the problem does not happen.  




MAG SPRING will cause the bolt not to lock back
Link Posted: 12/21/2008 9:10:24 AM EDT
[#7]
Ammo you were testing with?
Link Posted: 12/21/2008 9:12:12 AM EDT
[#8]
These are just suggestions. I hope others will chime in to help you out as well. I have to finish my Christmas shopping now, but I will check up on this thread tonight when I get home:


  • gas system is not allowing enough gas to push the bcg far enough to ingage bolt catch

  • mag spring is fatigued enough so that it won't activate the bolt catch in time

  • friends buffer spring fatigued or friends buffer is lighter than yours?




  • It sounds like you are short stroking. If the bolt doesn't travel back far enough the "spent" round may still eject. As the bolt is traveling foward it may not fully engage the next round in your mag passing the brass making it lift appropriately. As the bolt travels forward it collides with the side of the brass causing the dent. You should be able to simulate a short stroke using your charging handle at home. The question is, however, why is this happening? My guess is gas system. My psychic powers could be off though.




    Link Posted: 12/21/2008 9:14:07 AM EDT
    [#9]
    Link Posted: 12/21/2008 9:19:12 AM EDT
    [#10]
    Quoted:
    Check the spring length against these specs..........

    http://img.photobucket.com/albums/v489/Metroliner/bufferspg.jpg


    Not to argue. I believe the some of the chrome silicone buffer springs (if not all) are "flat wire" which means they would have to be longer to obtain the same compression resistance. Supposedly makes the system travel more smooth?
    Link Posted: 12/21/2008 9:28:03 AM EDT
    [#11]
    Link Posted: 12/21/2008 9:40:22 AM EDT
    [#12]
    Chrome silicone buffer springs are in fact longer and stiffer. I would like to know what kind of ammo was being used. If they were reloads that would be the problem I would think.
    Link Posted: 12/21/2008 9:45:03 AM EDT
    [#13]
    Yeah, I just measured mine. It is 15 1/8 inches.

    Quib, in your quest for absolute reliability, have you ever come across anything that you like that is not mil spec? The normal music wire springs are rated for 5000 compression cycles. Chrome silicone are rated for 500,000.

    ETA: You are well respected here. I just wish that you wouldn't shun product development so much. Eventually we may evolve.
    Link Posted: 12/21/2008 9:50:17 AM EDT
    [#14]
    Wow, I'm thinking of ordering some CS springs as long term replacements just to have.  Now I'll probably stay with the normal springs.
    Link Posted: 12/21/2008 10:00:09 AM EDT
    [#15]
    Quoted:
    Yeah, I just measured mine. It is 15 1/8 inches.

    Quib, in your quest for absolute reliability, have you ever come across anything that you like that is not mil spec? The normal music wire springs are rated for 5000 compression cycles. Chrome silicone are rated for 500,000.

    ETA: You are well respected here. I just wish that you wouldn't shun product development so much. Eventually we may evolve.


    I think, as I understand this, that product development is more important than reliability.
    We are talking about a $5 part that you could just replace after 1k rounds. Believe me,
    I am not arguing, but would not try to fix something not broken. I think i will order one
    right now...... and maybe a non-titanium firing pin too. Merry Christmas, BTW.
    Link Posted: 12/21/2008 10:05:52 AM EDT
    [#16]
    I had the same problem with mine so I installed Wolfe Xtra power springs wich were also to strong. I clipped a about three coils off to tweak to the right strength. Both my 20" are set up this way and function fine but will short stroke wolf and other under powered ammo. I beleive one xtra power spring manufacture suggests clipping coils off their springs to get the right amount of force. Many people here advise against clipping coils as they don't know what it does to the power curve of the spring but mine are stronger than spec springs through out the full length of buffer travel and feed and function fine. If you do decide to clip off a few coils be sure to put the clipped end into the buffer tube.
    Link Posted: 12/21/2008 10:10:51 AM EDT
    [#17]
    Quoted:
    Quoted:
    Yeah, I just measured mine. It is 15 1/8 inches.

    Quib, in your quest for absolute reliability, have you ever come across anything that you like that is not mil spec? The normal music wire springs are rated for 5000 compression cycles. Chrome silicone are rated for 500,000.

    ETA: You are well respected here. I just wish that you wouldn't shun product development so much. Eventually we may evolve.


    I think, as I understand this, that product development is more important than reliability.
    We are talking about a $5 part that you could just replace after 1k rounds. Believe me,
    I am not arguing, but would not try to fix something not broken. I think i will order one
    right now...... and maybe a non-titanium firing pin too. Merry Christmas, BTW.



    I hear ya. I wasn't taking money into the equation. I suppose it would be just as easy to toss springs in the trash and replace them.

    Addressing the titanium firing pin, "Change" doesn't necessarily mean going in the right direction.

    ETA: Have fun guys, I have to finish Christmas shopping. No hard feelings intended.
    Link Posted: 12/21/2008 10:28:54 AM EDT
    [#18]
    Link Posted: 12/21/2008 10:43:23 AM EDT
    [#19]
    Quoted:
    Wow, I'm thinking of ordering some CS springs as long term replacements just to have.  Now I'll probably stay with the normal springs.


    Std. springs last 5,000 to 10,000 cycles.

    Tubb CS springs last over 200,000 cycles.

    The Tubb flat wire springs are meant for CMP ammo (Mk262 or handload equivalents).  They might not work with .223 level ammo w/o cutting (yes, you can cut the spring to match your rifle/carbine and not reduce spring life).
    Link Posted: 12/21/2008 10:44:25 AM EDT
    [#20]
    CS AR action springs truly ARE a solution to a problem that does not exist.

    What everyone reading this post should do:

    Use GI action spring

    See that it works just fine (may need different buffers in some carbines though)

    Change every 5-10K rounds

    Why f––- around with anything else for an action spring????
    Link Posted: 12/21/2008 10:58:43 AM EDT
    [#21]
    Quoted:
    CS AR action springs truly ARE a solution to a problem that does not exist.

    What everyone reading this post should do:

    Use GI action spring

    See that it works just fine (may need different buffers in some carbines though)

    Change every 5-10K rounds

    Why f––- around with anything else for an action spring????


    Honest question to all, are you guys really changing the buffer spring every 5 to 10K? The reason I ask my Bushmaster has over 14K down the tube most of that is M855 using an H buffer and still works like a champ on the original spring.

    Link Posted: 12/21/2008 11:12:03 AM EDT
    [#22]
    I don't change mine until 5-10K, and only then as a preventative measure (not because of malfunctions or anything like that).

    Which is why all of us should wonder - what is the purpose of these super stiff CS action springs?
    Link Posted: 12/21/2008 11:16:14 AM EDT
    [#23]
    Another question where does the replacement guideline of 5 to 10K come from?
    Link Posted: 12/21/2008 11:20:43 AM EDT
    [#24]
    Quoted:
    Another question where does the replacement guideline of 5 to 10K come from?


    Nowhere in particular - just a product of my anal-retentiveness and a carryover of what I do with semiauto pistols.



    Technically I think you are supposed to measure the free length of the spring from time to time per the GI armorer's manual, and chuck it if too short.  Other than that, there is no replacement interval I'm aware of unless you're having problems.

    Link Posted: 12/21/2008 1:20:16 PM EDT
    [#25]
    Quoted:
    Ammo you were testing with?


    Well here's the funny part.  I shot 30 rounds of my own reloads at first, without a single malfunction.  I was testing out 55, 63, and 77 grain bullets, and I shot 2 5 shot groups of each.  No problems at all.  

    When I switched to Winchester White Box, that's when it all started.  Then I shot some of my friend's reloads, and still had the problem.  I used his mags, and my mags. . . Several of each, and the problem happened on all mags.  

    Also, when I swapped springs, I still used my H buffer.  

    I'm not sure how this could be the gas system b/c I completely solved it by changing to his recoil spring.  I did take my gas tube off during a thorough detail cleaning a couple months ago.

    Thanks for the posts guys.
    Link Posted: 12/21/2008 1:28:12 PM EDT
    [#26]
    Quoted:
    Check the spring length against these specs..........

    http://img.photobucket.com/albums/v489/Metroliner/bufferspg.jpg


    Ahhhhh. . . . This spring is 11 3/4". . . I need to call LaRue and let them know b/c they told me they only carried carbine length springs.  Looks like they may have gotten a shipment of rifle springs, and not known it.
    Link Posted: 12/21/2008 1:40:05 PM EDT
    [#27]
    Weak ammo + heavy buffer + strong spring = short stroking

    Try modifying one of the above to get a combination that works.
    Link Posted: 12/21/2008 2:33:55 PM EDT
    [#28]
    Link Posted: 12/21/2008 2:43:31 PM EDT
    [#29]
    Quoted:
    So I was having some issues on my 6920 b/c of a weak buffer spring.  I was a bit disappointed that my buffer spring only lasted 1500 or so rounds, so I wanted to get a much better spring.  I ordered the chrome silicon spring b/c I thought I'd never have to replace it.  

    My first outing with the new spring was yesterday, and. . . I need to replace it.  

    I got several rounds pinched by the bolt on the way into the chamber, and the bolt would not lock open after the last round.  

    I swapped springs and buffers with a friend's rifle (non-H buffer), and everything was perfect.   The spring says for carbine length guns, so I'm not sure why this spring is causing these malfunctions.  Any ideas or recommendations?  

    Thanks!





    (this is assumeing that everything else is in working order)I have 8 of these in my lmt lowers..put that cs spring back in.load 1 round in a mag.. fire it...if it does not lock back, clip ONE coil on that cs spring repeat these steps.Once it starts to lock back, you will be good to go.Also MOST standerd ar-15 springs SHOULD be replaced at about 4 to 5 k.The Tubbs spring is a lifetime part.
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