The border is obviously under federal jurisdiction, as well as anything that concerns first nations.
I heard someone say that there is no proof that the rule of law doesn't apply on reserves. To me, that is insulting the intelligence of police officers. I would really love to be able to remember a single firearms seizure operation on a reserve, but nothing comes to mind.
You are right to say that the solution requires joint and multi-stakeholder groups. In order for that to be socially acceptable, we have to bring in first nations police, along with federal, municipal and provincial police forces. We are lacking manpower, but we could be stronger together and everyone could bring their expertise to bear on the problem.