Read the instructions, its in there. I now send a letter with each Form describing the exemption because they really have no idea at the NFA branch of what they are doing.
Photographs and Fingerprints. An individual transferee, except if licensed as a manufacturer, importer, or dealer under the GCA, must (1) attach to Item 16 of the ATF Form 4, a 2 inch x 2 inch photograph of the frontal view of the transferee taken within 1 year prior to the date of the application and (2) attach two properly completed FBI Forms FD-258 (Fingerprint Card with blue lines) to the application. The fingerprints must be clear for accurate classification and taken by someone properly equipped to take them.
To make it easy to believe you need a FFL and a SOT to do interstate transfers, or have a FFL and a form 4. Either way you meet the requirements.