First off, this section pertains only to holders of Federal Firearms Licenses (FFLs). This does include Curio and Relic FFLs.
Firearms acquired and disposed of using your FFL must be logged. Although ATF will issue variances permitting you to keep your records on a computer, smaller shops and C&R holders frequently use a paper "bound book" carried by Brownells. Regardless of your method of logging, logging acquisitions made under your license is mandatory, and will entail the following fields:
Manufacturer/Importer: As indicated, this is either the manufacturer or importer of the weapon. Examples would be, for an M44 imported by Century Arms, "Century Arms". In the case of domestically built firearms, "Remington" would be an example of manufacturer, or for that matter "Stag Arms" or "Nodak Spud".
Model: In the above example of the Mosin-Nagant M44 from Century Arms, this is where you would write "M44".
Serial Number: In cases where the weapon has an importer's serial number, you would write the imported serial number here. Otherwise, you would write whatever serial number is on the receiver. Other parts may be swapped around, but the receiver is the weapon's "heart" by ATF standards.
Type: This field should be filled in with "rifle", "handgun", or "shotgun".
Caliber: Whatever the firearm shoots. In the case of the Mosin-Nagant, "7.62x54r" would be correct. In the case of bare AR receivers, whatever caliber marking is present on the receiver would be appropriate.
Date: The date at which the firearm entered your possession.
Name/Address or Name/FFL: The name/address or name and FFL number of the company shipping you the weapon.
-- SeanNewton - 21 Dec 2006