So without the numbers we can confidently say that there is a black market in weapons and this needs to be addressed. Now I thought, mistakenly obviously, that you had the AFTE for this. To do this you need to restrict the sale of firearms at gunshows, whether you want to call that private sales, or not, is irrelevant, you also need to restrict any reseller by requiring registration and transaction tracking, and you can put a transaction tax on it to pay for the paperwork
You see when things are out of control you need to go in hard and clean up the mess, forget it's just business and a little fun, and realise it is the source of a problem.