Just received an error letter from the NFA Branch regarding a machine gun I am selling to a dealer in my home state of Texas.  Basically it states there is a discrepancy in the barrel length and overall length according to their registry.  What I find interesting is that the information was copied directly from the Form 4 used to transfer the machine gun to me.  The gun in question is a very configurable BRP 76/45.  The gun was transferred from the BRP to my dealer originally.  Then my dealer transferred to me on a Form 4.  Is it possible it was missed several years ago and they are now examining a bit closer?

I plan to call them for advice, since even the fixed stock has been changed to a collapsible, so, either open or fully closed it does not agree with either their registry or my Form 4.  I no longer have the original stock.

The letter requests pics with a tape measure.  I can certainly do that and give them the current information, the barrel length will agree and just change overall length with the new stock collapsed.

Also, letter said to return to NFA Branch-05.  Does that indicate the examiner and does anyone know who that is, may help sort this out if I talk directly.

Should I send the form and info back registered mail?

OK, that,s about it, just seeing what the hive advice is and hoping the letter indicates approval may be forthcoming after fixing this, I need the money!

I've had barrel length questions directed to my dealer several times before about a m/g he had received on an form 3 or 4 and was transferring to me on a form 4. He was always able to work it out  and send a correction to the ATF.  But he was pissed because he had copied the info from a document that had transferred the gun to him and he had made no mods. I think the ATF is taking more time and checking the original records.
The phone call is a good idea and a registered mail return can't hurt. I sent a form 4 off a few weeks ago and got a return receipt a couple of day later, just to be sure that the form didn't get lost. They cashed the check in another week, so that was a confirmation too. I don't have a clue about which examiner it might be. It has ben my experience that they are working your form and the stamp will come within a week or so after they are satisfied with your corrections, holidays not withstanding.  

I don't really have anything to add about your main question, but I'd send the forms back priority or express mail.

Got an answer, looks like the way back original registry entry had the short barrel length listed, and that is what was checked by them.  Apparently, when transferred to me, it was a "don't care" or the configuration changed and the registry was not updated.  The gun is configured to my form 4 and to the new form 4 to the dealer that is purchasing it.  So, took pics, emailed them, did a cover letter, sent the error letter, forms and pics, so, hoping all is well.  Basically no changes  except the ATF will hopefully update the registry to the current configuration.  BTW, the current form 4 is dated 28 Sept, so, pretty quick to get the error letter back to me.  Maybe because it is a transfer to a dealer.