These parts can go on airsoft guns or on deactivated former firearms. The firearms themselves are prohib but you can do what you want with them in your dwelling. There is no crime here. If you have a license, you are flagged. Carry on
According to anecdotal evidence all firearms packages are going through CBSA inspections. If they Xray and see only accessories and no receivers or regulated parts they deem prohib then there will be a delay but it will pass through.