I’m guessing you can’t make a NFA gun as a ghost gun. What about something that follows the Remington TAC-14 for dimensions and using a ghost receiver?

If I understand the USC/CFR correctly, the TAC 14 is a Title I firearm and requires no markings if made for your own use.

Unless you own some very nice CNC machines good luck with finding a ghost receiver.

Finally, don't bring attention to yourself, on a dark and stormy night, unless you are positive the local LEOs have a good understanding of firearm's law.

The gun screams "sawed off shotgun with the serial number removed."

You can make an NFA item (SBR, SBS, AOW, etc., but not an machinegun) from the ground up using an 80% or even a "0%" receiver/frame.  However, you would still have to register that NFA item and pay the tax, same as all other NFA items.

The Remington TAC14 is not an NFA regulated firearm, so you could make such a firearm yourself using an 80% or other unregulated frame as a starting point without any involvement with the Fed. Gov., it's no different legally than making a standard rifle or pistol from an 80% receiver.  Just remember that firearms like the TAC14 do have specific requirements about OAL, not having a stock, and how the receiver is first built that ensure it remains just a "firearm" and not an NFA regulated weapon.

A serial number was required by the ATF when I did a form on my 80% ar lower. I even got a call from them to make sure I had the correct info on it before it was approved.

NOT to hijack your thread, but where are you finding a ghost/80% shotgun receiver?

Same question here.

It would not have to be an 80% receiver if you had the machinery to make a zero percent receiver out of a block of metal.

I speculate that in a few years we can just "3D additive print" any receiver we want.  ATF will become obsolete.  It is just a question of time.

80% AR lower with modified shotgun upper.

One of those .410 uppers?

Just don't put a stock on it and keep the overall length at 26" or longer, and you should be good to use a sub-18" barrel and have it be a "firearm" similar to the TAC14 or Shockwave.

Appearance wise, it would look like an AR pistol, but since it's smooth-bore, it must have the 26" minimum OAL and would be considered a "firearm"

Thanks.