I suggest a fictitious transfer program, spiderwebbed, private sales.
Since it is proven that federales cannot find islamists, run a healthcare program, track government covert bequeathed firearms, the tracking of 3000,000,000 private transfer, after the NICS data becomes obsolete, the spiderweb might be five years old before they begin to figure out the first actions.
You presume that they WANT to find them.
YOU, they can find. Bet your life on it.
That was my thought too. Everyone with black rifles make trades with others. Confuse ownership so much no one knows who has what. Make bills of sale on each trade to make it look like a sale.