Accu-Washer® Muzzle Device Alignment System

(17 reviews)
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Simply choose the correct size Accu-Washer® shim to accurately index your muzzle brake or flash suppressor while maintaining perfect bore alignment. Since only one shim is required, the tolerance stackups and complexities associated with peel washers and other multi-shim systems are eliminated. This minimizes the risk of baffle strikes, ensuring maximum accuracy and safety from your muzzle brake or suppressor. Includes 18 individually marked Accu-Washer™ shims (timing adjustable from 0-360 degrees in 20-deg increments) and easy to follow instructions. Precision machined from high strength 400 series stainless steel to a guaranteed thickness uniformity of ±0.0001". All shims feature an oxide blasted non-reflective surface finish for low visibility. One Accu-Washer System will align approximately nine brakes (on average) before replenishment shims are needed. Designed to fit 1/2-28 or 5/8-24 threaded barrels.

Note: The Accu-Washer Alignment System can be used with any brand muzzle device.


  1/2x28 5/8x24
O.D.: 0.750" 0.825"
Thickness: 0.060"-0.094" 0.060"-0.100"
Full Spec Sheet: View PDF
Installation Manual: View PDF

We recommend these for installing our:
M4-72 Severe-Duty Compensator
M11 Severe-Duty Muzzle Brake
M11-SPR Severe-Duty Muzzle Brake
EFAB (Enhanced Flash Arresting Brake)
AFAB (Advanced Flash Arresting Brake)




Crush washers are perfectly acceptable to use on any open aperture muzzle device, such as the standard A2 birdcage flash hider. However, our opinion is they should never be used on any baffle style muzzle device where the clearance hole is only slightly larger than the bullet. Firstly, crush washers come to a knife edge on both mating surfaces - it is likely for this reason that a muzzle device is already misaligned just sitting on the crush washer before it is even torqued down. More importantly, it relies on the principle that the washer will deform uniformly while it is being crushed. This requires that the material is uniform and that you apply a perfectly pure torque load normal to the bore. This is very unlikely (for anyone who has installed one) when you're putting all your might into the 30-60 ft-lbs of torque they often require. The consequence of this misalignment is a baffle strike causing bodily harm at worse and impaired accuracy at best.

On average, each pack will get you about 9 installations before a single replenishment shim is needed. Instead of increasing the price on all muzzle devices to include the Accu-Washer Alignment System, it makes more sense for a user to buy one pack separately and use it across multiple installations.

First, make sure the threads on your barrel and muzzle device are completely clean and free of all debris. Any contamination can limit the rotation. Next, applying a moly-grease or CLP-type lubricant to the threads on the brake and barrel will provide further rotation for the same torque. We suggest you apply generously, then run the brake on and off the barrel a couple times to work it in, then wipe up any excess. The coefficient of friction between the threads is what limits your rotation, cutting this coefficient in half with grease can give you twice as much rotation. You may also apply some lubricant to each side of the shim as there is friction in the works here too. Lastly, a little elbow grease. Since the Accu-Washer shims are used to adjust your brake in discrete intervals, it is inherent that the torque required for proper alignment will fall in a range. The torque load specified in the instructions is merely the minimum required so your device does not rattle free, however you will need to continue to apply torque beyond this to achieve alignment. Higher torque installs may require holding the rifle in a barrel vise.



For full specifications, installation manuals, and more - visit our Technical Resources page:


  • 5
    Never Use a Crush Washer Again!

    Posted by Brian Scocchio on 16th Sep 2022

    It's too bad that 5 stars is the best rating I can give, because these are worth so much more! I was a little skeptical of the price, but I read the reviews and decided to give them a try. I will never use a crush washer again. These are SO easy to time a muzzle device. First you put on the largest shim, and then put on the muzzle device hand tight. Either measure or estimate how many degrees you need to turn it to get it where it is supposed to be. Then you look up that measurment on the instructions, and select the shim that corresponds to that measurement. Take off the muzzle device, take off the largest shim, and replace it with the new shim. Put on the muzzle device and tighten it according to that device's instructions, and you muzzle device will be perfectly timed! I did this on 3 AR-15s, and the total time to do it was about 20 minutes It only took that long because I was going slow to make sure I did it right. If you use these you won't be disappointed!

  • 5

    Posted by JKing on 9th Aug 2022

    I was looking for a better option than crush washers or shims to properly mount a flash hider/compensator. Read a few articles about the accu-washers and decided to give them a try. I am SO glad I did!! They are so easy to use and mount as well as being a spot on fit to the barrel. The fit and finish of the product was also impressive. The instructions were simple and easy to understand. I received three separate e-mails concerning there shipping status which was a nice touch as well. Don’t hesitate, just get them, you won’t be disappointed!

  • 5
    Wish I had found these sooner

    Posted by Jerrod Leffler on 20th Mar 2021

    These are great. Gives you the ability to use one shim instead of worrying about stacking tolerances. Each kit has a wide assortment to help get your muzzle device timed just right. Great to have in the tool kit for any serious AR owner. I don't know what to do with all of my other shims now!

  • 5
    Muzzle Brake Install

    Posted by Richard LaMark II on 6th Mar 2021

    This product is fantastic! I have searched a long time for a product like this. Traditional shims are sharp, sloppy, unsightly and often time interfere with mounting a suppressor. With the Accu-Washer system, all these problems are solved.

  • 5
    Product Review

    Posted by josephmasanque on 19th Feb 2020

    Having said that, I’ve now done 4 muzzle devices (two Efab) on one accuwaher kit. It pays for itself!

  • 5
    Product Review

    Posted by guypatten on 16th May 2019

    These made mounting a new brake so easy. Was done in just about 5 minutes.

  • 5
    Product Review

    Posted by josephmasanque on 30th Nov 2018

    Worked perfectly the first time I tried. However, I did have to sand down a washer to get it to fit the last time. Still easier than using a peel washer I’m sure.

  • 5
    Product Review

    Posted by Sean Nguyen on 27th Jun 2018

    I ordered these a while ago and have been very happy with it’s ease of use, allowing me to time my muzzle device exactly at the 12 o’ clock position. I have OCD so when I say exact I mean on the dime exact, and everything aligns perfectly, something I cannot do with a crush washer. On Monday I ordered another set, and today which is Wednesday, it arrived to Washington state all the way from New York. These guys have excellent service and I’m very happy that I feel I should leave this review. I would recommend anyone looking to do a precise build on an AR system to get these shims from Precision Armanent, I would not do it any other way.