Ok its been since july since I read about it. But here is the official statement. "Registration not Required – Not Manufacturing: In response to questions from persons engaged in the business of gunsmithing, DDTC has found in specific cases that ITAR registration is not required because the following activities do not meet the ordinary, contemporary, common meaning of “manufacturing” that DDTC employs in implementing the ITAR and, therefore, do not constitute “manufacturing” for ITAR purposes: a) Occasional assembly of firearm parts and kits that do not require cutting, drilling, or machining; b) Firearm repairs involving one-for-one drop-in replacement parts that do not require any cutting, drilling, or machining for installation; c) Repairs involving replacement parts that do not improve the accuracy, caliber, or other aspects of firearm operation; d) Hydrographic paint or Cerakote application or bluing treatments for a firearm; e) Attachment of accessories to a completed firearm without drilling, cutting, or machining—such as attaching a scope, sling, or light to existing mounts or hooks, or attaching a flash suppressor, sound suppressor, muzzle brake, or similar item to a prethreaded muzzle; f) Cosmetic additions and alterations (including engraving) that do not improve the accuracy, caliber, or other aspects of firearm operation beyond its original capabilities; g) Machining new dovetails or drilling and tapping new holes for the installation of sights which do not improve the accuracy or operation of the firearm beyond its original capabilities; and h) Manual loading or reloading of ammunition of .50 caliber or smaller.

Activities limited to the domestic sale or resale of firearms, the occasional assembly of firearms without drilling, cutting, or machining, and/or specific gunsmithing activities that do not improve the accuracy, caliber, or operations of the firearm beyond its original capabilities (as described above) are not manufacturing within the context of the ITAR. If you are not manufacturing, exporting, temporarily importing or brokering defense articles or services, you are not required to register with DDTC."