Right, but they still cant use the 4473 legally for that. It would have to be infos given at the time of sale (or via owners of existing guns) by the FFL. Bottom line is they arent currently allowed exc for certain cases to access 4473s. Im sure they could find any number of ways around that.
Form 4473 page 3 section D
Box 26
Manufactuer or Importer
Box 27
Model
Box 28
Serial Number
Box 29
Type ( pistol, rifle, shotgun, etc)
Box 30
Caliber or Gauge