So I'm looking at picking up a complete HK german parts kit rifle with a flat. Being that I hear bending the flats and building them can be tricky, I was thinking of sending that stuff off to a smith to have done and then completing the assembly once it comes back to me. My question is, because you get the flat and it is not considered a firearm, and therefore no 4473 or Fa-10 is done upon acceptance, once it is completed into a functioning receiver does the gunsmith just send it back to me or does it then need to go to a dealer and I have to do all the paperwork? Or is this like a AR, where you don't do any paperwork until the rifle is finished and complete?