I met someone who told me they flew domestically with a licensed hunting rifle in NZ about 10 years ago and they were told to open carry the rifle onto the plane where the flight attendant locked it up.

Unrelated but Finnair's requirements for flying with doctoral swords are wonderful.

Big city or small town flight? Like anywhere, density changes everything. Certainly Auckland and Christchurch and Wellington have proper security procedures and facilities.

I'd believe it. In Australia, gun silencers (home made or otherwise) are absolutely illegal. In New Zealand no such limitations. A family member went to New Zealand maybe 15 years ago to somewhere suburban and found a few guys shooting animals in the distance - using silencers (I assume to not make too much noise for anyone nearby).

You can do it in the usa too. You need a special briefcase to lock your weapons and declare them at the counter. it’s a complicated, but possible