officers are confronted with a shotgun. >> reporter: the cost of converting the toy to a shotgun $30. but the dealers say it's a risky proposition. >> the fire's cartridge with the gun powder is an explosive. and the device has to be able to contain it pressure of that explosion. they are relying on maybe this will hold up. you would be putting a gun next to your head or are you putting a hand grenade next to your head. >> reporter: these zip guns or shotguns you make out of pipes are legal if you get the permit and if you get them approved. needless to say most guns made this way are not legal and they are not approved. megyn: there are some stuff questions for basic instinct