The gangs bring in plenty of drugs, they could bring in guns also.
In reality, gun control only applies to the law abiding, we have no hope of disarming the criminals.
In realty, most guns get into the hands of criminals via the legal gun market and lax laws that allow "law abiding good guys with guns" to profit by funneling guns into the grey markets. Thus, in reality, increased regulation on legal gun sales, transfers, registration, and proof of continued possession of all guns bought would massively choke of the illegal gun supply.
But would do nothing about the hundreds of millions of guns already out there. The government could confiscate some but there's no way they would get enough to matter. Ghost guns are already showing up more frequently as the skill level needed to make them is has gone way down.