Let's talk about AR15 buffer springs...

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  • TinCuda

    Sky Captain
    Apr 26, 2016
    1,556
    Texas
    I got to thinking about buffer springs when I was setting up my Ares Defense MCR. I used the buffer spring that came with the upper and a H3 buffer. I have re-posted a picture of the MCR along side of a standard carbine spring for comparison. The MCR is approximately 14 inches long with 34 coils and the stock carbine spring is 11 inches and 36 or 37 coils. I may have miscounted one or two but you get the idea. Both springs are made from the same wire gauge.

    Let me start by pasting a portion of an article I found on-line.

    "The springs for the rifle and the carbine are the same diameter, and made of the same steel alloy. The rifle springs have 41 to 43 coils, and the carbine springs have 37 to 39 coils. The brand-new length of the springs is approximately 12.75″ for the rifle and 10.5″ for the carbine springs. If you’ve bought a used rifle or carbine, and find that a spring has been shortened by cutting off coils, it should be replaced. (Any rifle that has a shortened spring in it also needs a complete inspection, as the spring was probably not cut without “reason.” You’ll need to find what the problem was that led a previous owner/armorer/gunsmith/hack to cut the spring.)

    Springs shorten with use. When a spring has gotten much shorter than the starting length, replace it. As long as a rifle spring is more than 12 inches long, and a carbine spring more than 10 inches long, they are still serviceable. When they have shortened to those lengths or shorter, replace them."

    At first, I thought Ares Defense might have just used a rifle buffer spring in a carbine tube. After a second look, that is not the case. It looks like Ares has their own dedicated (custom?) spring.

    My question is in regards to aftermarket springs. I have found several companies that sell springs. Heavy springs. Light springs. Flat wire springs. No specifications what so ever other than "heavy" or "light". There must be some kind of standard to work from. I like playing with guns but I can not see buying a dozen springs just to see what works best as an exercise in trial and error. These are machines and not really all that complex. I should be able to take one or two shots and be able to set the gun up.

    Up to this point, It has been real easy. The complexity that I am running into is that I am preparing to setup my MCR when I get my Franklin Armory Binary trigger. I had my MCR set up to eject spent shells straight out at the 3 o'clock. Franklin Armory suggests that if the rifle is set up to eject shells at the 1:45 to 2:00 position that you would get better results. They say it's less likely to have hammer follow. If that is the case (and I do not know if it is) then I may have to get into my buffer spring tension.

    So help me out guys. How do I even start talking about springs. Length, coils, pounds?


    .,
     

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    TinCuda

    Sky Captain
    Apr 26, 2016
    1,556
    Texas
    Does the upper have adjustable gas? If so, start there.

    Yes it does.

    This was really more of a question about springs in general. I have built ARs in the past. I understand the how and the why of what is going to need to happen to get this to work. I just have never needed to mess with buffer springs.

    I can not find a single place that has some kind of standard.

    If I go to any parts supply in the country and ask for the next higher gauge steel plate or the first over sized fastener, I would get the exact same thing from every supplier.

    What is the standard for a "orange" spring? I don't care if they want to color code the system. It's just one shop sells "Heavy" another sells "Red" and still another sells a "standard long".

    I am just trying to make sense of it.
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,644
    MoCo
    I don't think the flat wire Tubbs will work w the MCR. So ignore all those responses as the likely don't have one (I do and have tried just about every spring/buffer combo.) The factory spring is longer as to give a higher initial force and flatter slope. Takes a lot more force to strip them out of the links. I am an engineer and agree it's annoying that springs aren't spec'ed in kg/mm or some such like ALL other springs would be. I have my MCR spring and the full assortment of stock and Wolf springs. I could rig up a quickie rate tester and measure them for you (though will probably have to wait until Mon.) My dad was similarly pissed about 1911 recoil springs when he built one so he measured a bunch of their rates. I should post his data here on the forum somewhere too.

    Edit: I have all the sprinco springs, not the Wolfe.
     

    TinCuda

    Sky Captain
    Apr 26, 2016
    1,556
    Texas
    I don't think the flat wire Tubbs will work w the MCR. So ignore all those responses as the likely don't have one (I do and have tried just about every spring/buffer combo.) The factory spring is longer as to give a higher initial force and flatter slope. Takes a lot more force to strip them out of the links. I am an engineer and agree it's annoying that springs aren't spec'ed in kg/mm or some such like ALL other springs would be. I have my MCR spring and the full assortment of stock and Wolf springs. I could rig up a quickie rate tester and measure them for you (though will probably have to wait until Mon.) My dad was similarly pissed about 1911 recoil springs when he built one so he measured a bunch of their rates. I should post his data here on the forum somewhere too.

    Thank you, That would be really nice of you.

    I am in no hurry. This is a hobby for me. I will be out of town most of next week anyway.

    .,
     

    TinCuda

    Sky Captain
    Apr 26, 2016
    1,556
    Texas
    https://youtu.be/8fMVZbrnvu8

    OK, Thanks for the direction guys. I found this awesome video by Tubb's.

    I took some notes from the video: Position 1 is bolt forward. Position 2 is bolt aft.

    Standard new spring
    10.5 - 11 inch 32-36 coil (round wire)
    Pos 1 9.1 lbs
    Pos 2 16.7 lbs

    Standard Tubb's Spring
    36 coil (Flat wire)
    Pos 1 10.5 lbs
    Pos 2 16.3 lbs

    "308" Tubb's Spring
    42 coil (Flat wire)
    Pos 1 13.0 lbs
    Pos 2 16.7 lbs

    Competitor's Heavy Spring / Sprinco RED CS spring ?
    12 inch, 36 coil (round wire)
    Pos 1 10.5 lbs
    Pos 2 18.4 lbs

    Competitor's "308" Spring / Sprinco ORANGE (.308) CS spring ?
    36 coil? (Heavy gauge round wire)
    Pos 1 13.9 lbs
    Pos 2 24.8 lbs


    It also said you could cut coils off the 42 coil spring to reduce the force at 3.6 coils per pound.
    The last puzzle piece I need to get the full picture in my head is the force a standard MCR spring makes in each position. My guess is that it will fall very close to a standard (Heavy gauge round wire) "308" spring, maybe just a touch below.


    My guess on what I think the MCR Spring will measure is...
    Pos 1 11.5 lbs
    Pos 2 21.25 lbs

    additional information:

    Sprinco White spring
    10.5 inch 30 coil

    Sprinco Blue spring
    11 inch 33 coil


    .,
     
    Last edited:

    Magnumite

    Ultimate Member
    Dec 17, 2007
    6,564
    Harford County, Maryland
    One can be missing on the opportunity to custom tine the arm to themselves and the ammo they use by feeling one spring is the 'right' spring. Builders select components to achieve reliability and longevity of the firewarm. Buffers and spring selection will achieve smooth operation, flatter operation and other desirable outcomes. There was a thread a couples years back about this subject relative to shooting character of the AR pattern arm. Shooting and tuning a 1911 I can attest to the fact tuning does work. With my lesser experience with the AR I can feel differences. I haven't really tried it much since I have current determine what I prefer in an AR.
     

    TinCuda

    Sky Captain
    Apr 26, 2016
    1,556
    Texas
    One can be missing on the opportunity to custom tine the arm to themselves and the ammo they use by feeling one spring is the 'right' spring. Builders select components to achieve reliability and longevity of the firewarm. Buffers and spring selection will achieve smooth operation, flatter operation and other desirable outcomes. There was a thread a couples years back about this subject relative to shooting character of the AR pattern arm. Shooting and tuning a 1911 I can attest to the fact tuning does work. With my lesser experience with the AR I can feel differences. I haven't really tried it much since I have current determine what I prefer in an AR.

    I agree completely.

    I do not shoot for a living. I have a couple of good carry pistols that I would trust my life to and a shotgun for home defense. This is just for fun for me.

    That being said. My first goal would be reliability. I want the gun to go bang every time I pull the trigger. The only thing I have at stake here is possible embarrassment at the range and personal frustration.

    The next goals would be shootability and accuracy. I can mess with that later.

    Random thoughts on the spring subject.

    Hopefully this will all be academic. My MCR runs great right now as it is set up. H3 buffer and stock buffer spring. This is in preparation of when my Franklin Armory Binary trigger arrives.

    I am thinking of getting a Sprinco orange spring. It has the highest spring that I have seen tested. Pos 1 13.9 lbs and Pos 2 24.8 lbs. These are my thoughts, It has lots of power in Pos 2 to help strip the rounds from the belt. If the Binary trigger needs the bolt slowed down aft so much that it ejects the shell at the 2 o'clock position AND sped up forward enough to prevent hammer follow. The orange spring might be what we need.


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    TinCuda

    Sky Captain
    Apr 26, 2016
    1,556
    Texas
    I don't think the flat wire Tubbs will work w the MCR. So ignore all those responses as the likely don't have one (I do and have tried just about every spring/buffer combo.) The factory spring is longer as to give a higher initial force and flatter slope. Takes a lot more force to strip them out of the links. I am an engineer and agree it's annoying that springs aren't spec'ed in kg/mm or some such like ALL other springs would be. I have my MCR spring and the full assortment of stock and Wolf springs. I could rig up a quickie rate tester and measure them for you (though will probably have to wait until Mon.) My dad was similarly pissed about 1911 recoil springs when he built one so he measured a bunch of their rates. I should post his data here on the forum somewhere too.

    Edit: I have all the sprinco springs, not the Wolfe.
    I try to be patient, but I am kind of still waiting for those measurements. LOL
     
    Last edited:

    jonboyhst

    Member
    Apr 13, 2023
    21
    Park City KY
    I got to thinking about buffer springs when I was setting up my Ares Defense MCR. I used the buffer spring that came with the upper and a H3 buffer. I have re-posted a picture of the MCR along side of a standard carbine spring for comparison. The MCR is approximately 14 inches long with 34 coils and the stock carbine spring is 11 inches and 36 or 37 coils. I may have miscounted one or two but you get the idea. Both springs are made from the same wire gauge.

    Let me start by pasting a portion of an article I found on-line.

    "The springs for the rifle and the carbine are the same diameter, and made of the same steel alloy. The rifle springs have 41 to 43 coils, and the carbine springs have 37 to 39 coils. The brand-new length of the springs is approximately 12.75″ for the rifle and 10.5″ for the carbine springs. If you’ve bought a used rifle or carbine, and find that a spring has been shortened by cutting off coils, it should be replaced. (Any rifle that has a shortened spring in it also needs a complete inspection, as the spring was probably not cut without “reason.” You’ll need to find what the problem was that led a previous owner/armorer/gunsmith/hack to cut the spring.)

    Springs shorten with use. When a spring has gotten much shorter than the starting length, replace it. As long as a rifle spring is more than 12 inches long, and a carbine spring more than 10 inches long, they are still serviceable. When they have shortened to those lengths or shorter, replace them."

    At first, I thought Ares Defense might have just used a rifle buffer spring in a carbine tube. After a second look, that is not the case. It looks like Ares has their own dedicated (custom?) spring.

    My question is in regards to aftermarket springs. I have found several companies that sell springs. Heavy springs. Light springs. Flat wire springs. No specifications what so ever other than "heavy" or "light". There must be some kind of standard to work from. I like playing with guns but I can not see buying a dozen springs just to see what works best as an exercise in trial and error. These are machines and not really all that complex. I should be able to take one or two shots and be able to set the gun up.

    Up to this point, It has been real easy. The complexity that I am running into is that I am preparing to setup my MCR when I get my Franklin Armory Binary trigger. I had my MCR set up to eject spent shells straight out at the 3 o'clock. Franklin Armory suggests that if the rifle is set up to eject shells at the 1:45 to 2:00 position that you would get better results. They say it's less likely to have hammer follow. If that is the case (and I do not know if it is) then I may have to get into my buffer spring tension.

    So help me out guys. How do I even start talking about springs. Length, coils, pounds?


    .,
    I started running the Vltor a5 system with the Sprinco green spring in all my rifles and Carbines and have had zero problems, except for a friends homebuilt PSA 16" M4 and I think that rifle is badly overgassed, it still runs ok, we are just trying to work out the ejection pattern issue while running IMI M193.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    I started running the Vltor a5 system with the Sprinco green spring in all my rifles and Carbines and have had zero problems, except for a friends homebuilt PSA 16" M4 and I think that rifle is badly overgassed, it still runs ok, we are just trying to work out the ejection pattern issue while running IMI M193.
    If all else fails, go with a decent adjustable gas block.
     

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