Submitting new forms is sometimes (often?) not an option. In Dajowi's case, the returned forms were the original that were submitted to NFA and contained the buyer's (me) photos and, more importantly, the chief LEO's info and signature. Since we had to modify the original forms, it was Dajowi's good call to line-out the old info, initial it and resubmit with updated info.
Some valuable info was learned here, which is, I'm sure, obvious to those more experienced in such matters. First, the firearm descriptions have to match exactly between both Form 4s on a person-to-person transfer. Any deviance will get it bounced back.
Second, NFA discovered a discrepancy that neither the seller, the buyer nor the gun's original seller had noticed. The original Form 4 on a suppressor, completed by an SOT over a dozen years ago, had an "i" in place of a "1," which naturally caused some confusion to the examiner. She asked that a photo of the suppressor's S/N be sent to her with the amended Form 4 info, which was done.
Both Dajowi and I seem to agree that this was not a BS-kinda deal. The examiner actually caught a few discrepancies and/inaccuracies and sought to have them corrected. Better now than at some time in the future when, if numbers don't match up, it might prove ugly in the field. Or the cell.