@OldGrunt I live in NJ. You can legally buy/build an AR. I have two, AR556 (ruger) and one i built (psa parts). They just can't have more than one evil feature. If it has a pistol grip that's your evil feature. After that, you can't have an adjustable stock, flash hider (but pinned comps/brakes are okay... go figure), bayonet lug (because we all know the number of bayonet charges that have occurred), and threaded barrels (if you have one it has to pinned or be occupied by a comp/brake that is pinned). HOWEVER, mags are limited to 10rds.
So your friend could have had an AR all this time as long as it was NJ compliant.