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Thread: Which H buffer for a 20" barrel with collapsible stock?

  1. #31
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    Quote Originally Posted by VaniB View Post
    Ok....if the Canadian C7A2 operates fine on the lighter stuff.....I wonder now if I should use an H3 for the steady diet of 77 grain loads.
    bullet weight shouldn't have anything to do with it. 77gr loads are generally lower pressure, because they're generally loaded to SAAMI spec, rather than NATO. in fact, it's pretty hard to find 5.56 pressure ammo in anything heavier than 62gr m855... so if anything, if you're shooting a lot of 77gr ammo and you have to chose between buffer weights, the lighter buffer will likely be the choice to go with.

  2. #32
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    I don't think anyone can give you the answer you are looking for, not seriously anyway. What works in our rifles and our loads may nit work for you at all. My 18" SPR clone with a rifle length system runs fine with a standard carbine buffer in a UBR and carbine spring. Unfortunately, The only reliable answer to your question is going to be experimentation to see what works with your rifle and ammo.

  3. #33
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    I hate to break this to you, but you are going to have to try it out and see. Unless you can contact RRA and find out what gas size their ports are.

    My guess is that it is overgassed like many others.

    Quote Originally Posted by VaniB View Post
    I'm keeping everthing the same on this RRA NM rifle, and intend to keep firing stout loads of 77gr bullets. I simply want to take the RRA A2 fixed stock off of this rifle, and put the LMT SOPMOD stock and tube on it.

    This is really not such a rare and terribly unusual configuration. Here is the Colt Canada version of it:




    I'm sure before the Vltor A5 came along, this configuration had worked just fine. I'm just trying to determine which buffer will operate reliably while preventing a rifle length barrel and gas sytem from causing excess battering. I'm leaning with the H2 buffer at this point.


    And please guys, can you just accept it that.....I'M NOT DUMPING MY BRAND NEW SOPMOD stock and tube. If I hear "Vltor" one more time...



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  4. #34
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    Iraqgunz is right,the most positive route to take is try the different buffers with the ammo you plan to use.Test the function in both clean and fouled condition.
    If your going to run 5.56 NATO pressure ammo 100% of the time or heavy OTM's just run the H or H2 buffer.
    Otherwise the standard CAR buffer will/should run with just about any .223 Rem or NATO spec ammo,so I'd start there and see what you have.
    My builds are:
    -Armalite M15A4 20" SPR barreled uppers.
    -LMT M16 BCG's.
    -LMT Defender 2000 SOPMOD'd lowers.
    That said my next C7A2 type build will have an A5 stock assy.


    Here is a couple of the posts I made on the subject last year:

    "Im running two Armalite 20" M15A4 SPR uppers on LMT Defender SOPMOD'D lowers.Barrels are advertised as 1:9,but rod out closer to 1:8.
    In general I have found the CAR buffer to be the most widely acceptable of varying ammo in my rifles.Particularly .223 Rem spec 50-69gr.,which I use the majority of the time.
    The H and H2 run without issue with true 5.56 NATO pressure ammo(and some heavy OTM's).
    Overall I'd recommend getting the CAR,H and H2 buffers,run a selection of ammo and function test with the rifle to see which buffer is the best for you.
    As for gas port size on my barrels....I have no idea.I simply went through the buffers until the rifles choked with various ammo and made my notes.
    For more info do a search for C7A2.Several of the SME'S and IP's have posted a ton on info on this configuration. "




    "Here is one of the posts that KevinB,Nick and others discuss the buffer weight for the C7A2.

    https://www.m4carbine.net/showthread....highlight=C7A2

    What I gather from all the info provided in the past on the subject,the C7A2 buffer selection was based on overall performance as a do all plug and play with various barrel length uppers from 10"-20" and was tested and setup to run 5.56 NATO spec type ammo.
    As always I'd appreciate correction in my assumptions.

    In my experience with my weapons(sample of two non-govt standard) if lower pressure .223 Rem(particularly underpowered ammo like UMC or Wolf) is to be used the buffer selection will have to be explored as I noted above.

    HTH

    ETA
    On the balance of the weapon configuration.My barrels are what I call between HBAR and medium contour.With the SOPMOD,standard A2 handguards,ADM with Burris FFII Tactical 3x9x40 mounted foward the balance point is at the Delta.With a loaded 30rnd mag the balance point moves slightly rearward.
    YMMV "
    Last edited by Blankwaffe; 03-25-11 at 18:47.
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  5. #35
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    OP: That picture on the first page is the break down of how many tungsten and steel weights are in each buffer. If you already have a CAR buffer, buy a H3 and make the different weights from the components to see which buffer shoots reliably in your rifle. Get the heaviest weight that your rifle can fire but not short stroke and lock back and then go one lighter or keep it at the heaviest. At least this way, you don't have to buy three H buffers to see which one is best, and the cost is only the one buffer.

  6. #36
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    Quote Originally Posted by VaniB View Post

    And please guys, can you just accept it that.....I'M NOT DUMPING MY BRAND NEW SOPMOD stock and tube. If I hear "Vltor" one more time...
    The SOPMOD would still work with the Voltor tube wouldn't it?
    "Real men have always needed to know what time it is so they are at the airfield on time, pumping rounds into savages at the right time, etc. Being able to see such in the dark while light weights were comfy in bed without using a light required luminous material." -Originally Posted by ramairthree

  7. #37
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    Yes it would.

    I have a LMT receiver extension and I'm not a big fan of the dry lube coating they put on it. As of right now it's on the short list of things I need to sell.

    I also think just slapping the heaviest buffer possible is a bad choice. You're trying to balance buffer/spring with the gas system. Everytime you add weight to the reciprocating mass you are changing a few things. You may reduce the felt recoil on the rearward stroke, but now you have a lot of mass going forward, which is also a componet of the recoil you feel. I've tested it with the A5, and I plan on running a few different carbine buffers and see how it all comes out.

    With how soft my 16" intermediate shoots, I'm actually thinking of trying an AR15 bolt carrier, as opposed to the FA M16 one in there now.

    I would suggest buying more than one buffer and trying them out in your rifle, to see how it actually feels, and not depend on Internet advice w/o ever having felt the effects for yourself.

    G&R tactical has CMT buffers for very good prices. They are stamped correctly, unlike the RRA I came across at a local gun store. It was an H2, but didn't have any markings on the face.
    Last edited by bp7178; 03-26-11 at 12:20.

  8. #38
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    Quote Originally Posted by Iraqgunz View Post
    I hate to break this to you, but you are going to have to try it out and see. Unless you can contact RRA and find out what gas size their ports are.

    My guess is that it is overgassed like many others.
    What's the proper gas port diameter for a 20" barrel?

  9. #39
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    Quote Originally Posted by VaniB View Post
    Perhaps, I didn't provide enough info?... I already have the complete LMT SOPMOD collapsible stock

    If you already have the complete stock, go install it and see how you like shooting it the way it came. The complete assembly should have come with everything you need, so ignore the internet and get to shooting. If at some point you don't like the way it shoots, look at a heavier buffer then.
    Stick


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  10. #40
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    I have a 20" Colt upper and an running a H2 in a UBR. No issues with Wolf,Brown Bear and Nato 193/885.

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