It's been a while (2002) but I believe I just sent it to the generic NFA Branch address. I dug around and found the text of the letter I sent, FWIW:
December 12, 2002
I would like to request that a particular firearm be added to the list of Curios and Relics and have it removed from the purview of the National Firearms Act. The firearm in question is a High Standard Model “S” with the serial number 59493. These pistols are .22 Long Rifle caliber, but have smooth-bored barrels for use with shot shells. Other known examples of this rare pistol are all listed as Curio and Relics, but this particular one has apparently just come to light and this serial number is not among those on the C&R list.
In support of my request, I am enclosing three digital photographs, which show the following features of the pistol in question:
- The markings “HIGH-STANDARD MODEL “S”/ -.22 L.R. SHOT ONLY-“ which appear on the left side of the slide.
- The serial number “59493” which is stamped on the front of the grip.
- The last three digits of the serial number, which are stamped on the underside of the slide and show that the slide was original to this pistol.
If there are any questions you might have concerning this pistol, I may be contacted via phone at XXXXXXXXXX, by e-mail at XXXXXXXXXXXXX, or by regular mail.
I thank you for your consideration and look forward to your reply.