They could just as easily charge the ammo with a crime. They've done that already with firearms suspected of being used in "drug crimes". Those folks have to sue to get their guns back, even if they, the actual humans, are never convicted of a crime, and often they run out of money before the goverment runs out of yours. The politically incorrect parts of the fifth amendment are in no better oder with the policritters than the entire second amendment is.
Heck, they've done it with money found on people at the airport. No crime, no history of crime, no charges filed. The Centurians simply take your money, and send you on your way -- after giving the ticket agent her cut out of the take, for having reported you to them.
Happens all the time, at airports, on highways, etc.
There are some very ugly things going on.