I work at the airport and saw a USCBP officer walking around. I asked him about bringing in primers from us to Canada and he asked if I would be going through montana and I replied sure, I asked if I needed any paperwork or anything and he said no your fine to cross as long as Canada accepts it.
So take that with a grain of salt but that is what I was told today by them
So take that with a grain of salt but that is what I was told today by them