Accu-Washer® Muzzle Device Alignment System

(23 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.
  • Each shim is chamfered on one side to allow clearance for barrels with radiused thread shoulders.
  • One Accu-Washer System will align approximately nine brakes (on average) before replenishment shims are needed.
  • Designed to fit 1/2x28 or 5/8x24 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


Accu-Washer shim with chamfered edge

Shims are individually marked for easy identification


Accu-Washer shim with chamfered edge

Each shim is chamfered on one side to allow clearance for barrels with radiused thread shoulders


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

    Posted by Mike Fischer on 12th Sep 2023


  • 5
    Excellent product

    Posted by Zak Llamo-Cohen on 20th Jul 2023

    I used these accu-washers to reinstall 2 muzzle devices and it couldn't have been easier. They worked great and the instructions were very easy to follow.

  • 5
    Accu-washer alignment system

    Posted by Matt on 8th Jul 2023

    It’s pretty close doesn’t cut with me. Either it’s aligned or it’s not right. I tried multiple times fumbling around with peel washers and they just don’t work. This product is exactly what I was looking for. From now on this will be the only product I use to install and time muzzle devices. Well worth the purchase and could potentially work for several different installations.

  • 4
    Good product

    Posted by Charles on 26th Jun 2023

    The instructions were great and easy to understand. The packaging is ideal for hanging on to shims in the future.

  • 5
    Accu washers

    Posted by Dan on 19th Jun 2023

    It couldn’t be any easier. look at your muzzle break and guess the angle, use that washer from the instructions and your muzzle break is properly timed.

  • 5

    Posted by matt on 9th Dec 2022

    This is now my go-to system for all muzzle devices: easy to use and effective. Buy a few kits the first time and you're set. My crush washers and shims have been donated. Enjoy

  • 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!