A starting pistol or starter pistol is a blank handgun that is fired to start track and field races, as well as competitive swimming races at some meets. The sound and smoke of the gun going off serves as the signal for the athletes to begin the event. Starter guns "cannot fire real ammunition" without first being extensively modified. In most places, trying to "modify the replica is illegal." Beside sporting events, they are also used in films and in TV or stage shows.Blank shells or caps are used to prevent expelling projectiles, and only small amount of smoke can be seen when shot. Starting pistols may also include modified versions of standard pistols incapable of firing bullets, most commonly achieved by welding an obstruction into the barrel. This is less common nowadays, especially in Western countries. When electronic timing is used, a sensor is often affixed to the gun, which sends an electronic signal to the timing system upon firing. For deaf competitors or for modern electronic systems, a light may be used instead.
An issue with the use of starting pistols is that, since the report of the pistol is carried to the competitors at the speed of sound, which takes about 3 milliseconds to travel one metre, positions nearest the starter hear the report a few milliseconds before further positions. This issue is exaggerated in races where the runners begin in a stagger, putting a significant distance between the nearest and furthest runners. To avoid this problem, the pistol is in all major competitions wired with a microphone that transmits the sound virtually instantaneously to loudspeakers directly behind each competitor.
With security after the September 11 attacks on the US becoming prevalent and causing issues with starting pistols, a trend developed to use electronic starting systems that do not use pistols but use a "dummy" prop pistol which cannot function as a firearm and that is wired to the timing system. When the starter presses the button, they emit a signal to play a simulated gunshot that is broadcast to loudspeakers behind each lane, show a flash, emit simulated smoke[further explanation needed], and start the timing clock. Many venues have switched to the new format. Beyond the security concerns, it has also been observed that even with the use of loudspeakers, some competitors still wait for the actual sound of the gun to reach them, and since the new all-electronic starting pistols have no such problems, they became the official way of starting games at the 2012 Summer Olympics.