At my local range the same thing happened to a guy there. This was about 20 years ago when "silencers" where much less common. The guy had to talk to the police. I hear they questioned him on why he needed a silencer multiple times. Most of the police where surprised they where not banned in the USA.
"I ask, Sir, What is the militia?" "Its the whole of the people. To disarm the people is the best and most effectual way to enslave them" -George Mason Co-Author of the second amendment.