From Sea Coast Online:

Gun maker SIG Sauer has filed a civil suit against the federal Bureau of Alcohol, Tobacco, Firearms and Explosives claiming the federal agency wrongfully classified a “muzzle brake” SIG Sauer designed to reduce recoil as an item “intended only for use” when making a silencer.

SIG Sauer claims gun silencers are “subject to burdensome legal requirements,” and by calling its muzzle brake a part for a silencer, the federal agency is subjecting it to “economic injury.”

Much more at the link. The BATF refused to reclassify it even after SIG Sauer produced evidence that far from muffling the sound, it amplified it a bit.

Update June 24, 1014: See my post here for details.