You're welcome.
Last time I did that was 4 years ago, and I snail mailed it, but as long as you know it was acted upon, that's all that really matters.
I just copied an example request from the internet. Here's what that looked like:
Bureau of Alcohol, Tobacco, Firearms and Explosives
Attention: NFA Branch
244 Needy RD
Martinsburg, WV 25405-9431
RE: Removal of a SBR from the purview of NFA, Update of the NFRTR
To Whom It May Concern:
I would like to advise the NFA Branch that a Short Barreled Rifle previously registered by me on Form 1 has been permanently returned to a Title I status firearm. I am respectfully requesting that the National Firearms Registration and Transfer Record (NFRTR) be modified to reflect this change in status.
Lastly, I am sending this letter in duplicate and request that one copy be returned, along with a letter stating that the NFRTR has been updated to reflect the change in status.
Name & location of original manufacturer: Olympic Arms
624 Old Pacific HWY SE
Olympia, WA 98513
Type of firearm: Short Barreled Rifle
Caliber, Gauge or Size: 223
Model: M.F.R.
Length of barrel: 11.5" (now returned to 16")
Length overall: 30" (now 35")
Serial number: A12345
Thanking you in advance, I am
KitBuilder
and their reply about a month later:
Attached FileNote that ATF never actually removes a firearm from the NFRTR; they merely annotate the change.
There's no reason to wait for ATF's reply prior to proceeding with a Title I transfer, but I'd let the buyer know if they (or a future owner) wish to register it as a Title II (NFA) firearm again they should await your confirmation that ATF processed the letter.