The following series of images demonstrate how an M16 fires rubber coated steel bullets:
A blank cartridge is automatically loaded into the chamber from the magazine below. A rubber bullet must be loaded in manually from the end of the extension which is attached onto the end of the gun’s barrel.
When the trigger is pulled, the carrier assembly (‘hammer’) is launched forward and hits the blank cartridge, causing the gunpowder contained inside to explode.
The hammer and blank cartridge are pushed forward in unison up until the edge of the barrel.
High-pressure gas generated from the explosion of gunpowder from the blank cartridge travels through the barrel of the gun until it comes into contact with the rubber bullet lodged at the base of the extension.
High-pressure gas propels the rubber bullet through and out of the extension. Gas gets picked up into the gas port and travels backwards through the gas tube until it reaches the interior chamber of the carrier assembly.
Due to the extra gas needed to propel the rubber bullet, the pressure of the gas received back in the interior chamber is not sufficient to push the carrier assembly back into its default position and eject the spent cartridge along the way. Thus the gun must be ‘cocked’, manually returning the carrier assembly to its default position.
By returning the carrier assembly to its default position, the spent cartridge is ejected from the chamber.