As long as it says "Sporter" or "Target" or somesuch on the rifle, and it's fully postban, you should be fine. Ass guns are banned by name, e.g. "Colt AR-15", and by the usual six evil features in NJ. They use the same features as the fed ban. Also, magazines must be blocked to no more than 15 rounds.
For more info, go to [url]www.nationalccw.com[/url] hit the New Jersey Concealed cary link at the bottom. Go to the bottom of that page & hit one of the NJ Ass gun links at the bottom of that page. Kind of an indirect way to get there, but they have a way of keeping the same url at the top of all the pages.
Also, the law itself is accessible from [url]www.njleg.state.nj.us/[/url] and hit the "statutes" button. Do a search on assault rifle or weapon and you'll get the text of the law. It took a court decision to allow M1As and non Colt AR15 clones to remain legal for target shooting and, therefore, the rest of us.
HTH,
Norm