[DesertRhino]

Well, i hate to give you the bad news. But it turns out that each of what you refer to as a “scrubber” is actually an unregistered sound suppressor (silencer) for a pistol.
This violates the NFA and basically puts you in the category of people who own unregistered machine guns.

Recent ATF ruling.

[susannah59]

Some time ago, I saw a TV program about a murder (a true crime program) where the murderer had used a tennis ball to make a silencer. It was, in fact, one of the bits of evidence used to connect him to the crime.

Are they going to ban tennis balls, too?