The deals announced Thursday put five of Carolina's picks under contract. Quarterback Jimmy Clausen is among higher-round picks still unsigned.
Hardy is a defensive end from Mississippi, Pugh is a safety from Texas A&M and McClain is a cornerback from Connecticut.
The Panthers have also waived six players. Tight end Andrew George, safety Matt O'Hanlon, running back Daniel Porter, tackle Mark Ortmann, punter Blake Haudan and kicker Aaron Pettrey are all undrafted rookies.