Why shims are better than crush washers

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. First, 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 at worse and impaired accuracy at best.

We recommend our Accu-Washer Shim System for installation as they alleviate both of these issues providing the highest safety and performance from your device. Also, a peel washer or any precision multi-shim system are also perfectly acceptable methods for aligning your muzzle device.

Also consider that crush washers have the capacity to deform further beyond your install. So, if you happen to hit the muzzle on something with enough force you may permanently angle your device to the side killing your accuracy or worse: rendering the rifle useless.

Precision Matters

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.