Being from Jersey myself, I'm afraid I have to agree with some of the others. Jersey is just plain ridiculous with alot of things.
I have a distant relative that is an FFL, and we're close, and I wanted to pick something up for my Dad, and my relative just about hemmed and hawwed himself off the phone before saying, blood or no, unless I REALLY needed his help, he didn't want to get involved with Jersey. This was with a lever gun.
My experience with LEO's in this state regarding firearms has been very amicable, but hardly comprehensive. What I mean is, while they've been very nice, I have called the NJSP Firearms Division down in Trenton for clarification on certain things (shipment of ammo, etc.) and have gotten vastly different answers on different days. A paranoid would think they were keeping the policy on enforcement fungible so as to fit any situation they felt a need to fit. I actually believe that they JUST DON'T KNOW. If the Sarge in Firearms doesn't know, I hardly think the average patrolman is going to know, and when there is that much confusion, I am sure the $9 sale just isn't worth it to anyone when it may come with a trip through the PRNJ's labrynthine, multiple-interpretation firearm laws.
Also, I know that having a forward pistol grip on an AR is illegal in this state, pre or post. There is no such thing as pre-ban in NJ. I believe it's that any semi can only have a grip that is not forward of the action, or something like that.
Live Free or Die.
Vass