Let's try another idea...
First off, let me reiterate I'm on your side. I'd love to see good, purpose built silencers available- I've thought for years that designs like JCurts were perfect for the application. With so many two-piece barrels out there, since the tip is no more than just a long muzzle brake, why not make a suppressed tip?
But I'm also kind of cynical when it comes to our various wonderful governmental departments, and after who knows how many years of "arrest first, ask questions later", I need a little more reassurance than a single court case finding that itself acknowledges that both the law and the finding are vague.
So just hypothetically, let's try a scenario:
JCurt builds one of his units, and sells it to Joe Lotsasplatter. One afternoon, he's clearing his gear out of the car after a long day's play at the field, but the silencer falls out of his gearbag and he doesn't notice it in the back seat. Afterwards, he decides to drive to the nearest Gulp N' Blow for a burger, when he's pulled over for having a taillight out.
The cop notices the thing laying on the backseat, and upon examination, notices it's full of baffles and packing and looks for all the world like a silencer, except it has no maker's name nor an engraved serial number, as legal ones require. The cop arrests Joe and takes him in for booking.
Now, how would Joe use Crooker to keep from being charged with possession of an unregistered firearms silencer?
Better still, how would Joe use Crooker to keep from being arrested in the first place?