I don't think it's really considered smuggling. They're all legal items.
One of my co-workers went through some issues a couple years ago when he went down to the states and bought a Boyd's rifle stock for a 10/22 Carbine. Both are completely legal. However Customs and security took him aside and asked him all the routine questions and inspected the stock. And then CBSA pulled out their "bible of contraband" to see if they could take it. In the end they let him go, stock in hand.