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Thread: Nervous about changing muzzle brake on new 17

  1. #21
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    I am ready to swap out my stock MB for a Surefire SOCOM FH and Warden combo.
    I also got a FBA washer and peel washers for the indexing.
    In the process of the swap I noticed removing the stock MB was just simple.
    Two combo wrenches, one on locknut and one on MB, with the twisting effort mostly on MB.
    It popped loosed with mild effort.
    As I'm looking at the assembly to go on I realize the FBA washer is a nice small piece that helps spread the load across the shoulder profile on the barrel.
    I also notice the stock lock nut has the same qualities.
    The FBA washer measures .112" long. The threaded portion of the stock lock nut measures .135" long.
    What's the difference?
    The FBA has a full 360 degree bearing load to support and MB/FH device torqued against it.
    The stock lock nut has the same, if not more because there are at least two full turns of threads engaged, (but, area of contact on threads are smaller due to thread tolerances).
    Without getting into true measurements, I would say that both are great ways to support the barrel end devices, especially when only torqued to 25 ft. lbs. and using loctite.
    So at this point it comes to cosmetics and ease of assembly.
    The FBA washer will most likely need peel washers.
    (Note - This actually depends on how the piece is machined. Most CNC machines will start the thread at the same place consistently according the spindle. But production of the part may not machine a indexable profile at the same operation of the threads being cut.)
    My Surefire FH does not need peel washers to index perfectly using the FBA washer.
    Cosmetics?
    FBA washer, peel washers and Indexable device.
    Or
    Stock lock nut and Indexable device. (Note - peel washers will not be needed since the lock nut would be used to properly index your device.)
    Here are images of my research.
    With FBA and FH device, nice clean install because I don't need peel washers.
    20170311_140025_zpsc3gbs4u6.jpg
    Stock lock nut and FH device, also clean install but a little chunky with the nut being fatter than the end of the FH.
    20170311_140203_zps59b2yun4.jpg
    Anyway, it's just information to digest.
    300blkout thanked this.


  2. #22
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    TWO wrenches, back the jam nut off while holding the muzzle brake still and it will come off with ease. I put a little tape on the brake, tightened an adjustable wrench on it. No barrel removal, no armorer's blocks, no vise, no problem.

    I am shooting my SCAR with nothing but a thread protector while I wait for my KBA shoulder ring to come back in stock at PMM then it's time to install my Griffin Armament taper mount brake to use with my Recce 7 when it's finally out of NFA jail.

  3. #23
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    Quote Originally Posted by Fröman View Post
    TWO wrenches, back the jam nut off while holding the muzzle brake still and it will come off with ease. I put a little tape on the brake, tightened an adjustable wrench on it. No barrel removal, no armorer's blocks, no vise, no problem.

    I am shooting my SCAR with nothing but a thread protector while I wait for my KBA shoulder ring to come back in stock at PMM then it's time to install my Griffin Armament taper mount brake to use with my Recce 7 when it's finally out of NFA jail.
    So without blocks or a vise, how do you plan on torquing the new muzzle device?

    Sent from my SAMSUNG-SM-N920A using Tapatalk

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  5. #24
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    At 25 ft. lbs. you could hold the rifle between you knees and wrench that number.
    Use the rockset or loctite.
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  6. #25
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    Quote Originally Posted by JeepinDoug View Post
    At 25 ft. lbs. you could hold the rifle between you knees and wrench that number.
    Use the rockset or loctite.
    Great! For future reference, could you remove the muzzle device that has Rockset or loctite applied without a vice? I assume you would need a torch

    Sent from my SAMSUNG-SM-N920A using Tapatalk

  7. #26
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    Personally, I have zero experience with rockset but 242 Blue temporary Loctite is easy.
    Heat it once to around 300* surface temperature, too hot to hold onto.
    You want the thread locker around 250* or hotter.
    Let it cool to touch and heat it up one more time, same temp. You can break the threads hot or cold, doesn't matter.
    Just make sure it's really clean and dry before reapplying new Loctite.
    This also works for Red Permanent Loctite but not Green Loctite.
    The good thing is 300 degrees will not hurt anything.
    You need well over 1000 degrees to draw temper from the barrel.

  8. #27
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    Quote Originally Posted by 300blkout View Post
    Great! For future reference, could you remove the muzzle device that has Rockset or loctite applied without a vice? I assume you would need a torch

    Sent from my SAMSUNG-SM-N920A using Tapatalk
    Soak in water for 24 hours before attempted removal. Immersion in water for that amount of time will release the rockset.

    As fart as torquing the 25fl/lbs without a vise, I would like to see that. I tried to torque to 25ft/lbs IN a vise with vise barrel blocks and it still turned before I reached the amount quoted.

    Use a vise with some type of barrel blocks, either a 2X4 with a hole drilled down the center then cut in half or something similar. Use a smaller diameter drill bit than the barrel. Or use vise barrel blocks made of aluminum (what I have) and I use leather straps on either side of the barrel to lock the barrel in place with no damage or marring to the barrel.
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    "We hang the petty thieves and appoint the great ones to public office." - Aesop

  9. #28
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    Quote Originally Posted by HK SD9 Tactical View Post
    Soak in water for 24 hours before attempted removal. Immersion in water for that amount of time will release the rockset.

    As fart as torquing the 25fl/lbs without a vise, I would like to see that. I tried to torque to 25ft/lbs IN a vise with vise barrel blocks and it still turned before I reached the amount quoted.

    Use a vise with some type of barrel blocks, either a 2X4 with a hole drilled down the center then cut in half or something similar. Use a smaller diameter drill bit than the barrel. Or use vise barrel blocks made of aluminum (what I have) and I use leather straps on either side of the barrel to lock the barrel in place with no damage or marring to the barrel.
    Thank you! I will definitely be soaking in water before! I picked up some wheeler barrel blocks, so those should do the trick. Thanks again!

    Sent from my SAMSUNG-SM-N920A using Tapatalk

  10. #29
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    Quote Originally Posted by HK SD9 Tactical View Post
    Soak in water for 24 hours before attempted removal. Immersion in water for that amount of time will release the rockset.

    As fart as torquing the 25fl/lbs without a vise, I would like to see that. I tried to torque to 25ft/lbs IN a vise with vise barrel blocks and it still turned before I reached the amount quoted.

    Use a vise with some type of barrel blocks, either a 2X4 with a hole drilled down the center then cut in half or something similar. Use a smaller diameter drill bit than the barrel. Or use vise barrel blocks made of aluminum (what I have) and I use leather straps on either side of the barrel to lock the barrel in place with no damage or marring to the barrel.
    I do it all the time with naught but a set of Craftsman crow's foot wrenches and a HF torque wrench. Water for Rockset and MAP gas for loctite before I start cranking. Besides I'd rather rely 100% on a counter wrench than than applying direct torque to my barrel in a vise any day of the week.

  11. #30
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    Quote Originally Posted by Fröman View Post
    I do it all the time with naught but a set of Craftsman crow's foot wrenches and a HF torque wrench. Water for Rockset and MAP gas for loctite before I start cranking. Besides I'd rather rely 100% on a counter wrench than than applying direct torque to my barrel in a vise any day of the week.
    Unfortunately, for the SCAR17, there is no place for the counter wrench for installation otherwise that is the methodology I prefer as well.
    "We hang the petty thieves and appoint the great ones to public office." - Aesop

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