https://www.atf.gov/resource-center/firearms-trace-data-2017

Not too long of a read.

Didn't see an executive summary of our Republik's performance

What does the data presented mean??

click on NJ and you get NJ's numbers.

Some things you can determine from them: 

We recover a lot of rifles, and one of our top trace categories is found firearm (usually mid list in every other state), and we have more old people in possession than young people. To me this implies we run traces on every attic find someone turns in, or estates that the surviving relative hands over to the police to be rid of it. 

Like most other states, most of the guns are at least 3 years old or older, which implies that they are not being transported across state lines to undermine laws, but rather are stolen or otherwise misappropriated. 

NJ doesn't really have much of a gun problem by proportion. For example, Mississippi is less than half our population, and has about twice the traces.