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Thread: Installing comp/FH . . . does amount of torque affect accuracy?

  1. #1
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    Installing comp/FH . . . does amount of torque affect accuracy?

    Have you found accuracy affected after installing/changing a compensator or flash hider?

    If so, was accuracy affected by changing the amount of torque used for installation?

    Thanks!
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    Too much torque and you can “ring”/constrict bore- and that will affect accuracy.
    This more a thing with precision washers as opposed to crush.
    I’ve never played with MD torque values, but just snug them up.
    A true "Gun Guy" (or gal) should have familiarity and a modicum of proficiency with most all firearms platforms, as well as the major Food Groups.

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    Go to the 5.11 minute mark in this video from Criterion Barrels for their take on muzzle device torque:

    https://www.youtube.com/watch?v=aSi75yrTIKQ

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    The 15-20 ft pounds spec should absolutely be adhered to. I never trusted crush washers-- a pal in the industry tells me he loves them because if the muzzle doodad doesn't clock up right, he can go almost another whole turn. Yes, that is convenient and the theory behind crush washers is that they allow you to do just that while "giving" at just the right amount of pressure so you get all that rotation without increasing torque. But in a little bit of testing I found that yes, it's true, a certain level of torque is maintained but it's at about 40 ft pounds. Testing with gage pins I was able to induce these levels of barrel constriction at these levels of torque:
    25 ft. lbs, .0003
    40 ft. lbs, .001
    45 ft. lbs, .002
    60 ft. lbs, .003+

    Now, maybe, and I have not looked into this, maybe there are crush washers made to different torque-absorbing specs but the ones I've seen over the years are all look the same.

    This was one test one day, done by one guy, but.... for myself, I tend to favor "on the light side" for torque.

  5. #5
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    Thanks, guys! Great info!
    Last edited by Mean Bone; 10-27-20 at 10:53.
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  6. #6
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    Quote Originally Posted by Ned Christiansen View Post
    The 15-20 ft pounds spec should absolutely be adhered to. I never trusted crush washers-- a pal in the industry tells me he loves them because if the muzzle doodad doesn't clock up right, he can go almost another whole turn. Yes, that is convenient and the theory behind crush washers is that they allow you to do just that while "giving" at just the right amount of pressure so you get all that rotation without increasing torque. But in a little bit of testing I found that yes, it's true, a certain level of torque is maintained but it's at about 40 ft pounds. Testing with gage pins I was able to induce these levels of barrel constriction at these levels of torque:
    25 ft. lbs, .0003
    40 ft. lbs, .001
    45 ft. lbs, .002
    60 ft. lbs, .003+

    Now, maybe, and I have not looked into this, maybe there are crush washers made to different torque-absorbing specs but the ones I've seen over the years are all look the same.

    This was one test one day, done by one guy, but.... for myself, I tend to favor "on the light side" for torque.
    Have you tested the Armageddon Tactical Crush washers or the JP Enterprises double crush washers? I'd be interested to hear what you think about either of those two different designs. They are supposedly specifically designed to crush with less torque and be more consistent throughout their entire range of crush.

  7. #7
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    Ned, is the deformation/constriction elastic or permanent? If elastic then why not clock the muzzle device, deforming the washer, then back off and torque to 15 ftlbs?
    Thanks in advance,
    Mark
    Last edited by mpom; 10-27-20 at 08:22. Reason: spelling

  8. #8
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    Well the barrel ID isn't going to "spring back" to original ID dimension. It's steel.

    Think about this; the barrel is threaded for muzzle device. The treads are a tight spiral that terminate at the barrel shoulder where washer abuts both barrel and MD.

    The barrel muzzle threads are not 90 degree to bore/barrel, but are angled to allow MD to be twisted onto barrel- to contact washer and tighten MD to barrel.
    If you keep cranking the MD deeper into barrel you are doing so at an angle to line of bore. It is contacting one side or area of washer first, so washer is stacking pressure on barrel muzzle shoulder un-equally.
    A crush washer will be more forgiving in "kinking" or ringing barrel than a Precision/steel washer for the obvious reason the crush washer is designed to compress.
    Still, enough torque will eff up a barrel using a crush washer, same as a Precision Washer.

    I would use manufacture's recommended torque values or go EASY= enough torque to stabilize/prevent MD from loosening.
    A true "Gun Guy" (or gal) should have familiarity and a modicum of proficiency with most all firearms platforms, as well as the major Food Groups.

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    The only one I tested was one of many I had around that looked the same. Not surprised that JP came up with a solution, dang smart people there, and I'll check it and the Armageddon too. Not promising a test but let's see if I can make it happen.

    Mpom, that is so simple I'da never thought of it. I think it might ought to work. Because (Gaijin) at least in my little test, the bore did spring back. Now my test was not H.P. White grade-- it could have retained a few tenths' restriction and I might not have noticed.

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    Last edited by mpom; 10-27-20 at 12:19.

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