Thought I would share my story since I see some questions regarding 'carry nfa paperwork with you' etc.

My buddy has a friend that has some land that goes shooting every once and a while. I've been there before.  No issues.  We've had plenty of guys all line up at the same time and shoot.  No issues.
So we schedule another meet, my buddy brings his M16, and here is what unfolded.

So we all gather, start shooting all kinds of stuff.  5.56, 9mm, 12 gauge, etc.  Then we break out the M16 and do a quick couple of bursts.  Move on to other stuff, come back to the M16 quick couple of bursts.  The owner then tries to teach some non-gun friends to shoot the M16, etc.  Some more bursts.  I then do a full mag dump.  Set the weapon down and proceed to shoot some other semi-auto stuff.  Just as I'm about to pull the trigger I hear, "everyone hold up".  I turn around and see a cop walking down toward us.  All I'm thinking now in my head is "great, here we go."
First words out of the cops mouth is "WHO HAS THE FULL AUTO" in a demanding pissed off voice.  My buddy shows him the weapon, cop wants paperwork immediately.  My buddy pulls out his copies of his NFA paperwork for his M16 and SBS he has there.  The cop was examining the paperwork, asking questions like, "how do I know this is you", "i need to see your trust", " where is the SN located", etc, etc, etc.  We then proceeded to talk about 'what is what' and 'what we need', etc, etc.  After about 15 minutes of being a hard ass, he finally eased up.  The funny thing was, I had an MP5 SBR and he didn't ask to see my paperwork, which I did have on me.  I guess he was more concerned with the M16.
While we were talking to him, he was telling us that he also has NFA and transferred a Suppressor from his fathers trust to his.  So I would think he would know everything about this.  I kept scratching my head about why he was asking for his trust.  DIdn't make sense to me.

There is no law against shooting where we were.  He said someone called in a noise complaint.  He told us he couldn't tell us to stop shooting but he could come back for another noise complaint.  We put away the M16 and continued to shoot other stuff for the day.  It was both my buddy's and my first time dealing with a police officer dealing with NFA toys.

Beats me.  I don't live in that town so I'm not sure.  I know the guy that owns the property also hunts on his land.  The cop told us that the complaint came from far away.
I guess since the trees didn't have leaves on them yet, it was early spring, the sound traveled pretty far.  Maybe the people that called were scared, some old lady with her cats, who knows.

Form1 and Form4s should be all that is needed.  A SN, make, model, caliber on the form should be enough to identify the weapon/suppressor.
Trust, uh no.  You carry a Will with you just in case you die in a car accident?  People that have these on a LLC I'm sure don't carry around their business paperwork.

Yep I was thinking the same thing, but I also thought this would just give them a reason to come harass us.

We did offer to let him shoot anything he wanted but he declined.

The cop actually said that.  I was like some of these guys can barely afford to buy one AR15 let alone get into NFA.

I still think it is dumb.  Box 3B has the same address as my drivers license.

The other thing the cop asked was "how do I know that is your signature" on the bottom of the Form1/4.  My buddy was like, look at my drivers license.  Cop was like "it doesn't look the same".  I didn't even want to stir the pot by telling him, "guess what, the new eForms don't even have our signatures on it, they state, 'digitally signed'".
It almost seems like the BATFE needs to issue a 'get out of jail free' card when you are approved for NFA toys so you can show the fudds you are not a criminal.  Jeessh.