Purchasing a firearm in New Jersey is fairly straightforward, but don't be surprised if it takes upwards of six months (despite state laws requiring quicker consideration of your application) before you actually have a firearm in your hand. This guide is here to walk you through the process. Note that this guide is for getting a gun to defend yourself in your home. Like other restricted states, getting a permit to carry your gun in public is unlikely to happen unless you're famous, wealthy or have incriminating pictures of a high-ranking public official with a minor. If you have a question that is not answered here, or find a mistake (we're not perfect!), please contact us.
The first form you'll be required to fill out before you're (eventually) issued your is the STS-033, which is the State of New Jersey's primary form allowing you to exercise your 2nd Amendment right which is not to be infringed. The form contains the key questions which are likely to affect whether or not you're issued the permit(s). (Note that you can find all of New Jersey's various firearms-related permits here.)
Things in your background which could result in being denied a permit:
The process starts at your local police department. You can jump start this process by filling out the standard form STS-033 which is the form used statewide, and the Consent for Mental Health Records Search, form SP-066.
A couple of caveats to note:
After you've filled out the necessary forms and been fingerprinted (as of Feb. 2019, fingerprinting costs $52.66), next is the waiting game. The local police will send out a questionnaire to the references you listed, do their due diligence on your background, and come to a decision. You may want to stay on your references to make sure they return their surveys promptly.
If you're legally qualified and your references check out, you should receive your Firearms Purchaser's ID within 30 days—as is required by state law—however don't be surprised if it takes longer. If you feel you're getting the runaround after the legal 30-day period has passed, you can reference this step-by-step escalation guide from the New Jersey 2nd Amendment Society and you should also contact the Association of New Jersey Rifle & Pistol Clubs' Permit Strikeforce for information on how to proceed.
If you're interested in purchasing a long gun (rifle, shotgun), then you're good to go. Head to your local firearms retailer with your ID card and buy one of the few, legal, non-scary guns you're allowed to have in New Jersey. This ID card is good in perpetuity for the purchase of long guns in New Jersey.
If you want to purchase a handgun, the timer is ticking. Your purchase permit it is only good for 90 days (though you can request an additional 90 days from the local police chief) for buying a handgun and, futhermore, you can only purchase one handgun every 30 days. (Doing the simple math means that you can only buy a maximum of 3 handguns over 3 months without having to go through the application process again.)
When purchasing your handgun(s), yet another background check will be run, through both the NICS system, which is the nationwide database, and New Jersey's own system. The latter system can often return a result within moments; New Jersey's system can take up to 12 days, so be prepared for a wait.