Muzzle Shim / Peel Washer Comparison Thread

AR/M4 AR Technical Discussion
1

After having a pretty poor experience with a crush washer on a 7.62 build, I decided I would take the word of the community and upgrade to shims.

One of the common issues I encountered, first getting into the topic, was the variance of companies available and costs.

I am hoping, with this thread, we can post our experiences with the multitude of companies, what they provide, how they provide it, and if you feel like one company has a more effective product. It will help provide a better wealth of information for those searching in the future.

Considering crush washers are nearly as expensive as shim sets, I don’t see any reason not to use them in 90% of situations.

Last week I picked up 3 sets, 2 Gemtech and 1 PWS.

Right off the bat, I noticed two major differences: Quality and Quantity.

The Gemtech sets were $4.75 each.
The packaging for the Gemtechs is nice, doesn’t feel cheap, all the shims are separated within the packaging with the instructions. The packing felt 100% reusable for the shims I didn’t use.

I started out with the 7.62 build that inspired me, and found that only using 1 .41mm and 2 .25mm gave me the perfect rotation I needed to get my proper torque value. With that, I have over 10 shims remaining from that set.

The Package provided 13 Shims of varying thicknesses.
4x 0.075mm
3x 0.13mm
3x 0.25mm
2x 0.41mm
1x 2.0mm

I feel like these shims are very well made. Seem to be pretty square and appear quality. The only difficulty was mixing and matching thicknesses, figuring out what kind of rotation to expect from each washer.

The PWS Shim Set was $4.50 and provided 10 Shims
The PWS Packaging is simple, effective, and it contains a good set of instructions to follow when trying to figure out how much you need to rotate your muzzle device. Having their product running by degree of turns instead of thickness offers a simplicity not found with the thickness ratings.

However, opening the package effectively renders it (mostly) unusable at that point. You’ll have to find another way to re-store your shims and the instructions won’t be connected to the packaging any further.

The Package comes with:
1x Large Spacer (Giving 1 Half Turn of Rotation)
8x Medium Spacers (Giving 45* of Rotation in Each)
1x Small Spacer (Giving “smaller” degree of rotation) Which is very thin.

These shims will be effective, without a doubt, however the edges on the large washer seemed a little rounded. I highly doubt it would impact the “face” of the washer, but I liked the squared off edge feeling of the Gemtechs, in comparison.

[b]Overall, I will update this thread for giggles, at some point, in the future when I do more builds. I will pick up a company that isn’t already reviewed. Hoping someone here might be able to show off a Surefire packaging, what to expect and what you paid for it at the time.

Thanks if you read this far into a silly thread about shims.[/b]

2

I’ve always used Precision Armament’s “Accu-Washer” on muzzle devices that are just a few thou over bore diameter.
If tolerances are tight between exiting bullet and interior of muzzle device, a single, precision washer seems the way to go.
I’ve had bullets kiss a baffle with resulting crap accuracy. In these instances I’d used crush washer or stacked shim.

With a MD with more generous tolerances, this doesn’t seem to be as big an issue.

Generally speaking, re. compensators, the more efficient they are, the tighter the tolerances.

3

I also use PA set and will continue to do so. IMHO both sets reviewed ar inferior to the PA product.

4

I also like the Precision Armament accu-washers…I used them to mount my SF FH/suppressor adaptor. Work very nicely and easy to get timing correct. Definitely better than the SF supplied shims.

NC

5

I used the PA set on my MK12 build and on my 3 gun comp. easy to use for timing and very well machined.

6

Another happy customer for the PA kit.

It is important to read the instructions:

https://precisionarmament.com/v1/wp-content/uploads/2016/08/PRECISION-ARMAMENT-ACCU-WASHER-MUZZLE-DEVICE-ALIGNMENT-SYSTEM-INSTALLATION-GUIDE.pdf

Instead of reading the printed instructions I focused on the chart and ended up chasing my timing around. Pretty important to note that you start with the #18 shim installed hand tight in order to estimate the degree of rotation needed to time and then refer to the chart.

Not saying everyone is as dumb as me, but, read the instructions.

In the pack I bought there were 18 washers. They were marked with ‘bars’ with a light bar for ‘ones’ and a heavy bar for ‘fives’ so #1 is l and #5 is l with #18 being llllll

Very easy to use.

I bought mine from Brownells - https://www.brownells.com/rifle-parts/barrel-parts/rifle-barrel-hardware/washers/ar-15-1-2-28-accu-washer-system-prod54363.aspx

and later found that on the PA site they were $15.00 cheaper: https://precisionarmament.com/product/accu-washer-system/

Extra washers are $1.99 each on the PA site, so you can keep your kit complete.

The price may not be right if you are simply building ‘a’ rifle, but if you are putting together multiples, I think it is worth it.

7

Awesome review! I have to say, I will be picking up one of these kits shortly. They seem awesome, and I must have missed them in my google-fu when searching. Or I saw $20+ and subconsciously ignored them not understanding it’s a one washer system.

8

I dont have any suppressors so my muzzle devices are straight flash hiders and it appears I might be the last man on earth using peel washers. And I may only have one left lol

I hate crush washers, they always looked cheap to me. I first remember seeing them on lower end guns first, which is probably why. They became the norm and are usually just fine, Ive used a few but I still rather just time it and torque it. Id be all over shim kits if the device calls for it but rather not spend that money screwing on an A2

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9

Yes,
it’s a $25 kit, but should work for 9 installations.

10

But that’s only if you have 9 builds and each requires a correspondingly different starting point no? I.e build one requires 90*, build 2 100*, 3 120* etc?

If they all happen to require 90* you’re going to run out

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11

Maybe you should stick to using crush washers and be happy with the results. Replacement PA shims don’t cost anymore than a POS crush washer. If you don’t need the best don’t buy the best.

12

Who has only 9 builds?

Markm did that many last Thursday.

But seriously, that’s what they say. YMMV.

13

I’ve used the Surefire shim kit included with the Warcomp. Shims seemed well made but in order to get it timed correctly I had to use a couple of the super thin shims and they are delicate. As an included solution I give them a passing score, certainly better than a crush washer.

Also limited experience with the washers that KAC uses to install muzzle devices on their factory guns. These are thicker than the small Surefire shims, and only had 3 on my SR-15. They reinstalled to acceptable torque values when I experimented with remounting the 3 prong flash hider. I like these more than the Surefire shims.

By far my favorite is the Precision Armament washer kit. Totally worth the extra cost for the ease of selection and installation. For those worried about cosmetics the bead blasted matte finish of these washers looks more consistent with the parkerized finish on most barrels. I have yet to arrive at a washer that wouldn’t perfectly time a device between 20-35ft-lbs of torque, usually closer to 20ft-lbs. My SR-15 I have the Warcomp mounted on required 32ft-lbs to time perfectly. Since these are one piece items you don’t have to worry about a .001” washer getting twisted up against a thicker washer or barrel shoulder and ripping or getting damaged.

14

Awesome feedback on all systems discussed.

With the intentions of this thread being to educate, not only have I left with a better sense of options on the market, and an itch to buy them, but will surely help those in the future.

Sounds like PA is the go to, and based on a single washer with replacements costing 1.99, it’s stupid not to go to that system on the basis of cost and efficiency.

With that, I can’t lie that the bright silver was a small bother, but not enough to care more than a moment of thought to blacken it with sharpie or alumahyde and a qtip.

Thanks everyone again for contributing to, what is ultimately, a basic topic that can be solved with google-fu and some time. Hopefully we’ll be one of those resources for someone in the future.

15

Sure, I’ll get right on that bro

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16

I too like the PA system.

I also am a dumbass with ADHD and have messed up using the shims and had to order replacement shims – two times. The guys at PA are super helpful and shipping is quick.

17

Mounting Solutions Plus has them even cheaper. I recently bought an EFAB and they had the best price I could find. Forward Controls has them for the same price too, if you are already shopping there.

18

Are those of you using PA Accu-washers with SF muzzle devices also using said muzzle devices with suppressors?

19

I’ve got four rifles currently with PA Accu-Washers and Surefire muzzle devices (closed tine Warcomp, dual port brake, and two closed tine flash hiders). I run a SOCOM RC2 suppressor on all of them without issue. They are a whole hell of a lot easier to get aligned and torqued down than the included SF shims. I like to get as close to 20 ft-lbs as possible with perfect alignment using Rocksett and these seem to be the only way to do it that doesn’t leave you pissed off after multiple failed attempts.

20

Used the PA shims for the first time when I got an AFAB. It was a very easy install after reading the instructions.