I have experience with firearms manufacture and the ATF Tech Dept.
They maintain:
1) Assembly, refinishing, etc. = Manufacture period; i.e. if you park it you manufactured it and MUST have an FFL 07 if you do it for others since you are 'engaged in the business'.
2) 922® ONLY applies to the assembly of a long gun NOT posession.
3) Posession is NOT ifto facto assembly, and if it came with hicap mags then simply placing them into the firearms mag well is NOT assembly.
4) The LOCAL ATF branch has juristiction on this and MAY deside to investigate "who?" assembled it, but this has NEVE
