Even though the pistol had only been out a year when the film was made, a brand new HK45 was sanded and worn down to look very old (as the film takes place in a post apocalyptic 2043). The actual pistol is currently on display at the National Firearms Museum located at the NRA headquarters in Fairfax, Virginia.
Oh that movie was so dumb. But I did love the shootout in it because it was pretty much gonzo action.