I asked Tandemkross about exporting and customs and this is the reply I received.
"Thank you for your recent purchase.##
We can ship one order, every thirty days and it must less than $500US. Shipping prices do not count towards the $500US limit.#
At this time the only product we are not licensed to export to Canada are barrels. Magazines and the Double Kross Magazine bodies are not a problem for us to export.#
Once they reach customs they may require a duty fee, however this fee is out of our hands. We have had many orders of Magazines and the Double Kross mag bodies successfully reach out international customers. If in the unexpected chance the package did make it back to us, we can another#re-send it or refund the cost of the order, (depending#on the situation)
Each International Order that we receive is processed individually and this takes some time for us to complete. Export documentation and paperwork must be completed for each order as we must strictly adhere to ITAR regulations and restrictions. For these reasons, it may take up to two weeks for International Orders to be processed.
Let me know if you have any other questions.
Thank you,#
~
Kevin Miller
Customer Service Representative"
So it sounds to me like these should get through customs just fine. I sure hope so anyways.