Most of the bolt-action designs use rotating-bolt (or "turn-pull") design, which involves the shooter doing an upward "rotating" movement of the handle to unlock the bolt from the breech and cock the firing pin, followed by a rearward "pull" to open the breech, extract the spent cartridge case, then reverse the whole process to chamber the next cartridge and relock the breech. There are three major turn-bolt action designs: the Mauser system, the Lee–Enfield system, and the Mosin–Nagant system. All three differ in the way the bolt fits into the receiver, how the bolt rotates as it is being operated, the number of locking lugs holding the bolt in place as the gun is fired, and whether the action is cocked on the opening of the bolt (as in both the Mauser system and the Mosin-Nagant system) or the closing of the bolt (as in the Lee–Enfield system). The vast majority of modern bolt-action rifles utilize the Mauser system, with other designs such as the Lee–Enfield system and the Mosin-Nagant system only seeing limited usage.