Alabama Shooter, if you want to restrict a right, that puts the onus squarely on you to prove the benefit. You can't just say, "You want me to prove a negative?" and shrug it off.
The correct argument is, if you can't prove that your restriction of a right would have a demonstrable and readily proven benefit, you shouldn't even argue for restriction of the right in the first place.
Next, you point out that tens of thousands of transactions were stopped by the 4473 and NICS system. Please point out how many of those persons ended up doing prison time as a result?
(Last time I looked, at the end of the Clinton administration, the answer to that question was "2".)