I know that we do not have to legally inform BATFE if we permanently change the length of an SBR, but that they request it.
On the latest rev of the form 1, it states that the registrant "shall" notify of permanent changes.

Is the reason that we legally don't have to inform, is that there is nothing in the law making that an actual requirement? Like, the ATF is trying to make up requirements when there are legally no requirements for that, hence there cannot be a punishment for it?

There's no such thing as a permanent change.

This interests me as well, since I want to change the licensed configuration of one of my SBRs to a PDW configuration. 

Is there a law that says you have to notify the ATF if you change the configuration of the weapon?

I can't find a form for change of configuration of a registered firearm (or anything even remotely similar), so how would you notify them? Do you send them a letter? Call them on the telephone? 

If there is no form, then how can you prove that you notified them? How can they prove that you never notified them? A letter can simply be ignored or discarded without the ATF updating their records, couldn't it? 

Correct.

The law does not address changes to the configuration.

When you send them a letter notifying them off the changes, the ATF will send it back stamped that their records have been updated with a signature and date. I just got mine back after about 1 month of waiting.

Would you be able to post a redacted version of the letter you sent?  I'd like to do the same thing, but have no idea what to tell them.

I wanted to switch the caliber's between my two SBR's to try and make all of the information match my current configurations when I file the 5323.20 forms to take them out of state. The following is the letter I sent to the ATF/NFA. I sent them two signed copies and they returned one with stamped saying "Requested Adjustments made to the National Firearms Registration and Transfer Record" with a signature and date.


To whom it may concern:

On _______ & _______ (Dates of Approvals) I received two approved tax stamps to possess two short barreled rifles. The first one was registered for a _______(Manufacturer) AR-15 Lower receiver chambered in_______. It had a 7” barrel with the serial number being_______. My ID number is _______and my permit number is_______.

The second tax stamp that was approved was for a _______(Manufacturer) AR-15 Lower receiver chambered in_______. It had a 10.5” barrel and the serial number _______. My ID number is _______and my permit number is _______.

I want to inform you that I have permanently changed both rifles. The following are the currently configuration for both rifles:

_______(Manufacturer) AR-15 Lower Receiver
Model:_______
Barrel Length: _______
Caliber:         _______
Serial Number:_______
ID Number:_______
Permit Number:        _______

_______(Manufacturer) AR-15 Lower Receiver
Model:_______
Barrel Length: _______
Caliber:         _______
Serial Number:_______
ID Number:_______
Permit Number:        _______

If you require any more information about the permanent change, please let me know. Thank you for your time and consideration.
Sincerely,

Sign
Date

Awesome, much thanks!

I'm assuming you sent it to the same address as the original NFA paperwork.

William

Your welcome,

I used the eforms for both SBR's, but I sent it to the Needy Rd WV address.

bhughesru03,

Where exactly do get the "My ID number is __?_____ and the my permit number is ___?_____" from cause everything else is pretty much self explanatory ...

I replaced that with the control number for each of my forms.  Sent 2 letters out last week to the BATFE.  Will update here when I get a resolution.

William

I sent them a letter telling them I was permanently changing the barrel length with a copy of my approved Form 1. I never got anything back, but I heard that is normal with ATF

I just post a picture of my lunch to their facebook page, because it satisfies just as many legal requirements.

Much thanks, I'll be patiently waiting ...

Juan

I have built 4 sbrs.  After a few years I had them all in the various configurations that I intended them to stay forever.  In my mind they were permanent changes.  I wrote a letter and let Martinsburg know the current and permanent destriptions.

About two years later, I got a personal phone call from a supervisor in Martinsburg. I had submitted a change letter and  one of the changes had her very confused.  I had changed both the barrel and the stock  on one of the guns.  That change changed the barrel length without changing the overall length.  She asked that I write them again and explain exactly what I had done to change the barrel length without changing the oal.  

She again asked me to explain why I was writing the letter changing the description of 4 guns.  She said that was not necessary as there was no such thing as a permanent change to an AR15 platform.  I said, "OK, but I don't want any problems when I am dead and you get Form 5s that don't match the Form 1s.  She said good point, but again there is no such thing as a permanent change to an AR15 platform.

I wrote the letter she asked me too and about 18 months later got a letter confirming the change to the 4 guns.

So, no more letters for me.  It just confuses them.  There is no such thing as a permanent change to an AR15 platform, according to Martinsburg.

The  only thing good that came out of the whole mess, is that I had a Form 4 pending when she called me.  I mentioned that I thought she might be calling about a problem with my Form 4.  She said NO, it had nothing to do with that.  The Form 4 got approved about a week later.  I have no clue if she had anything to do with that.

In summary, there is no such thing as a permanent change to an AR15 platform.

So you are saying there is no such thing as a permanent change to an AR15 platform?

Was I too subtle?

What if I just want to go back and forth between uppers changing the calibers ...

You may do so.

Without having to notify ATF/NFA?

Yes, without having to notify the ATF.

Why is there so much confusion about this...

Its a request, not a requirement that you notify the BATFE in writing any PERMANENT changes of your SBR.

Considering the fact that an AR15's barrel length can be changed by pushing two pins, its not permanent by any stretch of the imagination unless you as a individual have zero intent of ever changing it back.

Got my first letter back.  They sent back one of my signed copies with a stamp and signature indicating the registry has been update.  Total turn-around time less than 3 weeks.

William