Storing them with someone else could definitely be construed as a transfer.
Additionally, attempting to conceal assets during a divorce could cause you a whole heap of trouble if you don't do it correctly. Sometimes even then.
If you were to say rent an apartment, and moved your safe in, that would probably be legally ok. In all my reading I have not found anything that states storage must be done at your primary residence. But it may not fix your problem.
If you want a real answer, consult a lawyer. Especially if the primary concern is the wife claiming threats or violence. If the lawyer isn't ocncerned with you getting next to nothing for them, find a friendly FFL who will put them on "consignment", and some buddies willing to get permits to buy up the favorites really cheap.
On the upside, if the wife walks off with them, NJ law means that she has just committed a buttload of felonies.
On the other hand, if she just dumps them in the fire place and lets them burn, you are pretty much screwed. Happened to one guy I met.