My family and I were discussing an old Columbo episode in which the victim was killed by a particular caliber of bullet. The suspect that Columbo tailed for the entire episode (Robert Culp), though he owned handguns, owned none of the caliber that was used in the murder. At the end, Columbo proves the murderer guilty by discovering an item hidden in a lamp. "A calibration converter," he says. "That was a sweet touch. I never would have thought of that." And we see that the calibration converter is a cylindrical device which slides into the barrel of a handgun. Now, one of us in the discussion is studying criminal justice, and neither he nor the rest of us had ever heard of a calibration converter. Nor could we figure out how, if this device slips into the barrel of a gun, it isn't violently ejected when one fires the weapon. I Googled this term, and most of what I came up with was either electronics, or other references to that Columbo episode. I even checked a handgun site and found nothing about it. Only one web page made a passing mention of it, and I think they were talking guardedly about using weapons for illegal purposes. So does anybody know about calibration converters? I'm just curious, because if it weren't for the reference above, I'd be tempted to pass it off as a Hollywood scriptwriter's invention. And if they're real, how do you keep them from ejecting when the gun is fired? Does this device have any legitimate purposes, or is it mainly designed to deceive law enforcement? If the latter, how come you don't hear more about criminals using them?