Exporting anything firearms related can turn into a nightmare pretty quickly, trust me.
It's not that complicated.
Choose a factory that is on the DDTC list. Noveske is compliant.
Apply for import permit from Canada. I can usually fax it in and receive it the same day.
Fill out Department Of State form DSP-83 and wait 30-60 days for approval.
Department of Commerce for shotgun parts.