1. The laws which charter the ATF give the ATF authority to regulate firearms, NOT parts which can be added to firearms.
2. The Constitution restricts the federal government’s law enforcement powers to interstate commerce, and therefore prohibits the ATF from regulating goods such as suppressors which originate in one state and remain in that state.
The original “charter” for the ATF was a taxing agency. They lost that shred of Constitutionality when Bush moved them over under the DoJ.
We let them ignore smaller parts of the Constitution. Now, they just don’t give a sh*t...