I've had many dealings with customs.

For simple B709s for ammo even firearms never had any real issues. Cops were even speedy when they knew customs was already holding stuff.

Had incidents with the pricks over other stuff though. Knives. I collect them. I had a very rare antique confiscated and presumably destroyed when returning from India they said the hareem jamdhar punching two bladed knife was illegal. Gave me a form but said it had to be applied for before bringing to Australia, so presumably a waste of time. Later someone told me, no, you should still have applied for as they have to consider the application if it was confiscated at the airport. I even asked them to donate it to a museum rather than destroy it. There were TWO of those in Johdpur of that age, over 400 years old. That one and one in a museum.

And nowadays customs or border force, loves tobacco taxing. I hate tax collectors of any sort. It is a Biblical thing.