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Thread: Best way to hold upper while TQ barrel nut?

  1. #21
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    Quote Originally Posted by bigwagon View Post
    I'm having a hard time visualizing how a clamped receiver would prevent the pin from shearing with a seized barrel nut compared to a reaction rod. Either way the force is going through the pin.
    What Eric D. said, it's pretty simple to understand really... The threads on the barrel nut are usually seized to the threads on the upper, the inside clamp face of the barrel nut and the upper receiver extension flange clamp face don't usually become seized to the barrel extension flange.

    This is why/how you can shear an index pin by using upper receiver vise blocks to remove/install a muzzle devise even though the barrel nut was properly torqued to spec. The friction clamping the flange is less than the friction between the threads of the barrel nut and upper receiver.
    Last edited by 556Cliff; 01-04-16 at 18:13.

  2. #22
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    Quote Originally Posted by 556Cliff View Post
    What Eric D. said, it's pretty simple to understand really... The threads on the barrel nut are usually seized to the threads on the upper, the inside clamp face of the barrel nut and the upper receiver extension flange clamp face don't usually become seized to the barrel extension flange.

    This is why/how you can shear an index pin by using upper receiver vise blocks to remove/install a muzzle devise even though the barrel nut was properly torqued to spec. The friction clamping the flange is less than the friction between the threads of the barrel nut and upper receiver.
    I have guys that work for me that could tear up an anvil in a sawdust pile with a rubber mallet

    With a little judgment and proper technique any of the barrel installation methods can be successful.

    and without it you can make a mess of something as simple as installing a receiver extension.

  3. #23
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    Quote Originally Posted by rcoodyar15 View Post
    I have guys that work for me that could tear up an anvil in a sawdust pile with a rubber mallet

    With a little judgment and proper technique any of the barrel installation methods can be successful.

    and without it you can make a mess of something as simple as installing a receiver extension.
    I know people like that.

    Iv used antisieze the upper delron block
    And hand turned the nut on and off the upper with out the barrel on it

    Sent from my SM-G900P using Tapatalk

  4. #24
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    Quote Originally Posted by Eric D. View Post
    Let's assume seized means that the threads of the receiver are fused to the threads of the barrel nut such that any applied torque to the nut creates a tendency for the entire receiver to rotate. With an unsupported receiver that rotation is largely opposed only by the indexing pin (some opposition is created by friction between the receiver face and barrel extension shoulder). With a supported receiver most of the rotational opposition is taken by the supporting fixture. With a supported receiver the only force directed through the pin is the result of the rotational tendency created by friction between the barrel nut and the barrel extension shoulder.
    Isn't the point of the reaction rod that it locks the barrel in place and prevents it from turning inside the receiver? It seems like that would isolate the stress on the pin, unless the barrel extension starts to unthread. Maybe that is what happens. I'd like to see an example of one that has done this.

  5. #25
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    I use aluminum barrel blocks. But some people don't like having to remove the aluminum marks left on the barrel after wards.

  6. #26
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    Quote Originally Posted by bigwagon View Post
    Isn't the point of the reaction rod that it locks the barrel in place and prevents it from turning inside the receiver? It seems like that would isolate the stress on the pin, unless the barrel extension starts to unthread. Maybe that is what happens. I'd like to see an example of one that has done this.
    You understand that the barrel nut is threaded onto the upper receiver, right? To 'properly' loosen the barrel nut, you secure the upper receiver (male threads) and apply a rotational force to the barrel nut (female threads). If you use a Reaction Rod to secure the barrel instead and if the barrel nut & upper receiver are seized (or over torqued) the entire assembly (barrel nut & upper receiver) will rotate, putting pressure on the index pin because it is being held firmly in place.

    I'm not saying it can't be done that way but it's not the "right" way to do it.

    Think of a nut and bolt with a large washer in between. To remove the nut, wrenches are placed both on the nut & bolt. You don't secure the washer in a vise and just loosen the nut. If the nut & bolt are seized, they will just spin on the washer. You need to apply a direct rotational force on the female threads (barrel nut) and secure the male threads (receiver) & not the medium held in between (barrel).

    IMO, a Reaction Rod is only properly being used when installing/removing muzzle devices. Not that they won't work for removing barrels but it's not really correct the tool.
    Quote Originally Posted by JSantoro View Post
    Stop dicking the dog, please. It's gross.

  7. #27
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    Quote Originally Posted by cemoulton View Post
    I use aluminum barrel blocks. But some people don't like having to remove the aluminum marks left on the barrel after wards.
    The aluminum marks can be avoided and a better grip on the barrel can be achieved by putting something like leather or those blue paper shop towels in between the blocks and the barrel. Anyways, using barrel blocks for barrel nut installation/removal can lead to sheared index pins as well with the added possibility of potentially loosening the barrel extension.

  8. #28
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    Quote Originally Posted by 556Cliff View Post
    The aluminum marks can be avoided and a better grip on the barrel can be achieved by putting something like leather or those blue paper shop towels in between the blocks and the barrel. Anyways, using barrel blocks for barrel nut installation/removal can lead to sheared index pins as well with the added possibility of potentially loosening the barrel extension.


    I imagine non of the methods are with out risk.

  9. #29
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    https://www.m4carbine.net/showthread...and-vise-block there are additional links in this thread.

  10. #30
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    Yes it happened. Key word was OVERTORQUED barrel nut without any anti-seize and the barrel nut was seized to the upper. Having said that I have done well over 500 uppers since I have had it and that has been the only issue thus far. You do have to be smarter than your equipment and what you are working with.

    Quote Originally Posted by tb-av View Post
    There was a picture here not two weeks ago of a sheared pin. Also I believe Iraqgunz said he had 1(one) shear upon dis-assembly of a highly over torqued nut.

    It's pretty well known that it can happen.



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