Looks like Indiana is about to legalize hunting with a silencer as long as used legally and with the permission of the owner of private property. Illegal use of a silencer would be either a Class C or Class B misdemeanor. For the text of the bill or current status follow this link.
There are several type of Class 3 items that are restricted by the National Firearms Act.
Each state can impose additional restrictions on the sale, purchase, and transfer of class 3 firearms in addition to the compliance that is required with the national Firearms Act.
In Indiana you can own the following items that are regulated the the National Firearms Act
Machine Guns Silencers Any Other Weapon (AOW)