Whether the federal definition of a firearm silencer requires a showing of subjective purpose or intent to use a device as a silencer

Question Presented Federal law defines a firearm silencer as “any device for silencing, muffling, or diminishing the report of a portable firearm.” Does the word “for” in the federal definition require a showing of subjective purpose or intent to use a device as a silencer, as the First, Sixth, and Seventh Circuits have held, or can a firearms expert permissibly testify that a device is a silencer based on its objective characteristics and that its intended use is irrelevant to culpability, as the Ninth Circuit ruled in this case? i Statement of