Knights in Fake Armor?

S1 E4: It's clear that this is no ordinary pawn shop as the Pawn Stars wheel and deal items ranging from an old school Pac-Man to a Medieval Jousting Helmet. If these items are as real as their owner's say they are--they could be worth up to $30,000! Then, an old timer brings in a pristine 1884 Trap Door rifle that the guys buy hoping that it still fires. But, when the gun range owner says that simply firing it could cause a "catastrophic malfunction" the guys decide it's time to bring out their human guinea pig.