They only smack you with a river salmon if you ship to the West coast. Central, they body check you into the boards. East coast, they keep it for fishing but, will say “sorry about that” like a bunch of times.
Really, if the CBSA opens it (they don’t check them all) they will try to “flip/flick” it open with one hand. If they can it may be stopped, if not it goes through. Tighten down the pivot if possible. If it’s not a flipper or thumbstud, but rather a two hand open like a traditional or lock back, then no issue at all. If they do stop it, they send you a nice letter and you can get it return shipped. I’ve ordered several from US since they started this BS and have not had any stopped. I did have a flipper from overseas stopped, but that was right after they changed the rules and I was able to have it returned.