Review: White Sound Defense FOSSA-556

The White Sound Defense FOSSA-556 is one of the newest muzzle devices on the market. WSD claims that this device will decrease muzzle rise and recoil while still suppressing flash on par with some of the best flash suppressors on the market – all without the over-pressure issues that compensator/muzzle brakes typically process. It shows WSD’s typical flair for high end materials, high performance coatings, and innovative engineering, but does it do what it claims?



The FOSSA-556 is a flash suppressor that also decreases muzzle rise and recoil. It is not a muzzle brake/compensator that also suppresses flash. That is a small, but important, distinction.

It is machined from 17-4PH stainless steel and then finished with a titanium aluminum nitride surface coating. The combination of the steel used and the coating should make it very corrosion resistant and resistant to the adherence of carbon.

The FOSSA-556 has three flash suppressor tines. The bottom one is the largest and takes up nearly 180 degrees of the FOSSA’556’s circumference. The top two tines are smaller and the gap between them is located at the top center of the device.  It uses a unique internal geometry and the orientation of the tines to mitigate muzzle rise and recoil.

Observations from Use

The most surprising thing to me is the FOSSA-556’s flash surpressing capabilities. Will at WSD told me it would be good but I was still surprised and impressed. This device suppresses flash on par with some of the best devices out there. It appears to outperform devices like the YHM Phantom (a very good device in its own right) and perform slightly better than the Smith Enterprise Vortex. I tested it with Prvi Partizan  75gr Match and Federal 55gr .223 bulk pack ammo through a 16” barrel (Spikes GMP upper) and there was little to no visible flash perpendicular to the shooter.


There are only a handful of flash suppressors out there that will perform as well as this in terms of flash suppression but the FOSSA-556 also boasts some muzzle rise compensation and recoil reduction. It does this by means of the closed bottom and open top slot configuration along with some unique internal geometry. It works very well. I was expecting it to display a lot of downward pushing because of the open top slot, but it was surprisingly neutral. There was little in the way of downward movement or side deflection. I wouldn’t say it was as neutral as a PWS FSC556 or Surefire muzzle brake but it is very impressive for a device that is primarily a flash suppressor.

The FOSSA-556 is similar to the previously reviewed PWS Triad in that it is a flash suppressor that also controls muzzle climb and recoil. However, I found the FOSSA-556 to be more stable in terms of side to side movement during recoil and less likely to push the muzzle down than the Triad. Both are great devices and users will have to weigh the cost difference when deciding.

Perhaps most importantly, it manages to provide this muzzle rise mitigation with no extra concussive blast or perceived noise to the shooter or those around the shooter. I also noted that it had minimal ground signature thanks to the large bottom tine. It was similar to a Phantom with 5C2 in terms of ground signature.

White Sound Defense has engineered a clever fix for that annoying pitch fork like ringing that is so common with devices with long, uniform thickness tines like the FOSSA-556. I can’t go into too much detail here other than to say it works (there are patents pending). I never heard the FOSSA-556 ring even with electronic hearing protection in use. It is actually pretty interesting that is doesn’t ring because when it is off the carbine it rings readily but once installed, it is completely quiet.

The coating on this device has a really attractive dull gray look to it. It is a very good looking device. Normally, when I install a muzzle device, I try to be at least a little careful to keep as much of the finish intact as possible. I took no such precautions with FOSSA-556 so that I could test the durability of the coating. I would usually put a bit of grease or oil on the flats to protect the finish but I didn’t this time. The coating didn’t really hold up that well when faced with an adjustable wrench and no protection. It fared about as well as a black phosphate coating which is disappointing. The difference is that there is stainless steel underneath. It does however do a fairly good job of releasing carbon. The device wiped clean fairly easily with just a rag. White Sound Defense tells me that they are already have a solution for finish issue.


Wrap Up

This device is really pretty amazing now that I have had a chance to put it through its paces. It is a very effective flash suppressor that also happens to provide an impressive degree of muzzle rise mitigation. It also manages to mitigate the downsides that typically plague other devices: pitch fork ringing and concussive side blast. The coating didn’t hold up as well as I would have hoped but on the whole, this is an impressive device.

You really should check out the FOSSA-556 at

Disclosure: I received the FOSSA-556 from White Sound Defense, free of charge, for review.

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2 Responses to Review: White Sound Defense FOSSA-556

  1. Arete13 February 18, 2013 at 19:04 #

    “The FOSSA-556 has three flash suppressor tines. The bottom one is the largest and takes up 180 degrees of the FOSSA’556’s circumference.”

    Sure doesn’t look like it takes up 180 degrees judging by the first picture. I’d say 150 degrees

    • Matt February 18, 2013 at 19:22 #

      That should have read “nearly” 180 degrees. Thanks.

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