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  1. #1
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    Suppressor mounts and shims/crush washers

    I'm going to preface this by saying I am using the included shims and following the instructions from the manufacturer...

    But for those of you with far more experience than me (which is a fairly low bar, BTW), my question is thus: why can't I use a simple crush washer with the flash hider mount?

    I've read about how a crush washer doesn't always compress evenly and may therefore leave the mount angled and increase the chance of a baffle strike. I get that the manufacturer can tell me to go pound salt if I don't use the recommended install method and then have an issue. But with the tight tolerances for threads on both the barrel and the suppressor mount, plus the precision with which the suppressor fits on the mount, it seems to me that any slight variation in "crush evenness" from a crush washer would be immaterial given that the barrel/mount mating surfaces serve to keep everything in alignment and would override any slight variation in pressure at the rear of the mount imparted by a crush washer.

    What am I missing here?

  2. #2
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    I'm just confirming that you want to install a suppressor mount with a crush washer?

    Guessing just for the simplicity?

  3. #3
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    The tolerences of the threads are far from accurate enough to correctly align a muzzle device. I would not even trust the shims as they just reference the barrel shoulder. Always check the alignment with an alignment rod IMO. I’ve had high end barrels come with a out of spec shoulder. It’s not as uncommon as you think.

    Crush washer will almost always cant the device.

  4. #4
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    Quote Originally Posted by PJD642 View Post
    I'm going to preface this by saying I am using the included shims and following the instructions from the manufacturer...

    But for those of you with far more experience than me (which is a fairly low bar, BTW), my question is thus: why can't I use a simple crush washer with the flash hider mount?

    I've read about how a crush washer doesn't always compress evenly and may therefore leave the mount angled and increase the chance of a baffle strike. I get that the manufacturer can tell me to go pound salt if I don't use the recommended install method and then have an issue. But with the tight tolerances for threads on both the barrel and the suppressor mount, plus the precision with which the suppressor fits on the mount, it seems to me that any slight variation in "crush evenness" from a crush washer would be immaterial given that the barrel/mount mating surfaces serve to keep everything in alignment and would override any slight variation in pressure at the rear of the mount imparted by a crush washer.

    What am I missing here?
    It's more than them just telling you to go pound salt.

    The risk is yes that of a baffle strike, but also your gun could have really bad POI shift too. I saw one guy recently who had like two feet of POI shift from unsuppressed to suppressed.

    He ultimately got his muzzle device installed correctly and afterwards his POI shift was down about 2 inches.

    Basically everything has to be right. The barrel axis, the threading, the shoulder, and even if those are ok and the mount is installed wrong you can run into a lot of problems aside from baffle strikes.

  5. #5
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    Also you have to pay attention to the orientation of the muzzle device too. On my devices if the mount is installed sideways or upside down it will cause a bigger POI shift. In other words, yes it gets that specific.

    Some cans and mounts you don't need to worry about timing them, but others you definitely do. This is in addition to making sure that everything is lined up with the right bore axis and all that. It does make a big difference.

  6. #6
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    Quote Originally Posted by UWone77 View Post
    I'm just confirming that you want to install a suppressor mount with a crush washer?

    Guessing just for the simplicity?
    No. I'm using the shims that came with the mount. It's more of a theoretical question than anything.

    Good information from all. Makes sense now. Thanks.
    Last edited by PJD642; 7 February 2018 at 12:57.

  7. #7
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    The only suppressor manufacturer that I know of that allows crush washers on muzzle devices is B&T. One of their Rotex suppressors mounts on A2 flash hiders, and gets issued all across Europe on HK 416s with crush washers. I believe the bore size is rather large so any slight misalignment doesn't matter.
    Will - Owner of Arisaka LLC - http://www.arisakadefense.com

  8. #8
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    Quote Originally Posted by Slippers View Post
    The only suppressor manufacturer that I know of that allows crush washers on muzzle devices is B&T. One of their Rotex suppressors mounts on A2 flash hiders, and gets issued all across Europe on HK 416s with crush washers. I believe the bore size is rather large so any slight misalignment doesn't matter.
    Seems like it would be a good idea for everyone to have a slightly larger bore to prevent baffle strikes. The strikes I've seen have almost always been just a small slight strike. Might affect over all db numbers, but doubt it would be noticeable to the shooter.

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