What's up with 80% lowers in NJ.

Can you build it? Own one? Or bring one that was built and etched to NJ?

I searched and info i got was very old.

(I was being sarcastic about question never asked if anyone thought otherwise)

NJ prohibits the manufacturing of firearms unless one first obtains a license to manufacture firearms.  To do so is a violation of 2C:39-9d.  Completing an 80% lower is manufacturing (as you're taking something that is "not a firearm", and making a firearm out of it).

There is no specific law against owning an 80% lower.  But the minute you perform 1% of work on it, in NJ, the ATF considers it a firearm, and NJ considers you to have manufactured a firearm.

However you go about legally acquiring a firearm outside of the borders of NJ, is beyond the applicability of NJ laws.  Just as you may legally acquire a long arm in another state from an FFL, and transport it back into NJ, you can do the same with an 80% lower that has been turned into a firearm.

So - to answer what you're probably really getting at....   yes, you may legally purchase an 80% lower as a resident of NJ, transport it outside of the state, finish it into a working firearm, then transport it back into NJ and possess it here.

Of course, since the above reads like specific legal advice, I should also advise that I am not an attorney, and the above is simply my lay opinion on the matter - NOT to be construed as actual legal advice.  You are strongly encouraged to seek competent counsel on the matter, from a licensed attorney familiar with NJ's intricate firearms laws, before actually engaging in such activity.

I had bought a 1911 jig and 80% receiver to finish. Then found out it was illegal here. Since I didn't feel like owning a $230 paper weight and didn't want to deal with the hassle of taking it out of state to finish and then run the risk of getting caught with it in NJ I returned it. It just wasn't worth the hassle and uncertainty.

Your best bet is to forget that 80% anythings exist anywhere in the world until after you move out of this piece of shit state and into a free one.

bringing it in, possibly... already done outside of here.  just would have to mark/etch it up.

There is no Federal requirement to mark or etch any information on a homemade lower unless it is being registered as an NFA weapon.

From the NJ state law perspective I would view this the same as buying a muzzleloader out of state.  A completely legal and unregulated activity.

apparently it would seem the saying, better safe than sorry would apply in NJ.  just because the feds may not require it, doesn't mean NJ gestapo wouldn't throw felonies at you for having a firearm without any markings.  

ooooooohhhhh ghost guns are icky

True.  Though it would be a stretch, it's possible to be charged with 2C:39-3d for possession of a "defaced" firearm, said definition being to "remove [...] the name of the maker, model designation, manufacturer's serial number or any other distinguishing identification mark or number on any firearm".

True, you can't remove something that was never there - but I can see where you wouldn't want to get into a "if a tree falls in the forest" argument with a prosecutor in front of a jury.

It's perfectly legal to engrave your own serial number if you're really worried about it

From what I understand so far, an 80% receiver is not a firearm. An 81% receiver is a firearm.  Manufacturing, in this case, would be defined as turning the 80% receiver into an 81% receiver.  I'm thinking that it would be legal if I put an 80% receiver and a cordless drill in my car, drive over the bridge to PA, drill a hole or two to "manufacture" an 81% complete firearm, and finish it in my home shop in NJ without the need to finish it to a functioning firearm outside of NJ.  Is this correct or is there a fed or PA law prohibiting this?

No PA or federal law prohibiting this.  Unfortunately, the only way to find out (for sure) if it will pass muster in NJ is to do it, get caught, get prosecuted, and get a verdict.  If it's not guilty, then you're good to go  

"GUILTY UNTIL PROVEN INNOCENT " NJ.

"AND EVEN IF YOU ARE FOUNT INNOCENT WE'RE STILL GOING TO TREAT YOU LIKE A BOTTOM FEEDING CRIMINAL AND STRIP YOU OF WHAT LITTLE RIGHTS WE ALLOW YOU TO HAVE!!!!"