1. What laws govern production of firearm parts in the US?
and
2. What are the import laws regarding importation of said parts?
OK, I'm not an expert. I'm gonna give you my understandings:
1. Some parts are ungoverned for the most part. Moving parts such as slide, trigger, grip, hammer, safety slide release, springs etc. that are of factory original design fall under this. Where it gets tricky is if you try to do something wild like make a full auto conversion kit or something. Those are STRICTLY regulated. Improved parts such as a different design to the trigger or hammer or what have you are fine as well. Large capacity magazines might be illegal in some states. The basic USA definition of the firearm itself is what is regulated, not so much after market parts. The firearm itself is considered the reciever which is the portion that has the serial number.
2. Certain firearms are prohibited for importation even today. Parts may fall under the same laws. You would need to contact the BATF to find out. Also, there may be additional custom fees and such (I import ornamental stone [granite] on a large scale so that is a consideration for me). Federal laws may vary from individual state laws (sic: california). Also there may be requirements for a certain amount of liability insurance for the parts you sell.
Hope that helps. Not as detailed as I would like, but at least a starting place.
