I got the story from an eyewitness;
Two guys examining a pump shotgun in a house (I'm not sure of the make or model).
The guy holding the shotgun pointed the gun in a safe direction and worked the pump (finger not on or near the trigger). Shotgun went BOOOOOOOM into a dresser.
No one was hurt.
So, a knowledgeable shotgun person took the shotgun apart and said that it had been modified.
I've also read that the firing pins can get stuck if the gun hasn't been cleaned.
This might be a dumb question (I don't have a pump shotgun), but how would a shooter know if a pump shotgun is loaded without working the action?
And, how would you know if it's been modified?