It's my understanding that the gun was prepared by Detonics for Stenbridge; a guy who would rent blank firing guns to the Hollywood movie crowd. It actually shoots and ejects 9mm blanks that are loaded by Remington. The bore is 45 size at the muzzle. You can't tell in the movies that it's not ejecting 45 shells; they fly out too fast. Detonics also prepared blank firing guns in Combat Master size for Miami Vice and Magnum P.I. (I think Magnum P.I. also got a Scoremaster sized one). A blank firing Pocket 9 was prepared for "The Equalizer" series. Tom Sellek liked the blank guns so much that he ordered real ones, which were "slicked-up" in the trigger pull, etc, by the head gunsmith before they were shipped.
...Deeton