From what I could tell, AKs have been classified as an "assault firearm" for years. Assuming that the OP has gotten correct info, there are huge legal problems with the NJAG doing this.
- If it was legal to possess when you purchased it, and you purchased it legally (& I have no reason to think otherwise), how does the AG suddenly make possession a crime? That's a separation of powers problem, as your AG probably doesn't have legislative authority.
- Has the legislature recently passed something that allows the AG to confiscate them?
- Has the AG "interpreted" a statute to mean he or she can confiscate?
- Is someone going to pay you for your AK? If not, I'd call it a taking without just compensation.
- I'd be looking for a paper trail, and making copies of everything I found. A move this big can't happen without someone putting together a memo.