barrel, keeping chamber pressures created by the blank high enough and for long enough to cycle the firearm's gas-operated action. In the case of non-crimped blanks, it also serves to pulverise the plug to prevent it leaving as a projectile. Specially designed blank-firing prop firearms are sometimes used for movies, thereby avoiding gun control legislation and increasing the margin of safety because they cannot be loaded with live ammunition. 5-in-1 blanks are specifically made for theatrical use and are commonly used in real firearms for dramatic effect. 5-in-1 blanks can function in a variety of different calibres, hence the name. Special blank cartridges are also used when the explosive power of a cartridge is needed, but a projectile is not. Blank cartridges were commonly used for launching a messenger line, tear-gas or rifle grenades, though some types of grenades are capable of trapping the bullet of a live round. Larger blanks are also used for line launching guns, such as the line launching kit for the Mossberg 500 shotgun. Blank rimfire cartridges, commonly called power loads, are also used in some nail guns (powder-actuated tools), where the power is tapped to force a heavy piston into the nail, with enough force to bury its full length into steel or concrete. Some forms of fast draw competitions use special blanks that are loaded with a layer of slow burning rifle powder on top of a thin layer of faster-burning pistol powder. The pistol powder ignites the slower burning rifle powder, and fires it out of the barrel much like a shotgun shell. The burning powder only travels a few yards before it completely combusts, but that is far enough to burst the balloon used as a target for those competitions. Wax bullets are also commonly used for competitions and training where a non-lethal projectile is required. A blank cartridge was sometimes also issued to a randomly selected shooter in an execution by firing squad, on the theory that each of the shooters would take comfort in the fact that they may not have fired a live round. This tradition dates back to before cartridge arms, when a muzzle loading musket would be loaded without a ball. Some abattoir Captive bolt pistols are powered by blank cartridges. Blank 12-gauge shotgun cartridges are also used in "alarm mines", devices that use a tripwire to produce an extremely loud report in order to alert