Bolt action
When the bolt is opened, the first cartridge in the gun is loaded.  After firing the gun, opening the bolt takes out the empty cartridge, and closing the bolt puts in a new one. Bolt action rifles are usually the most accurate type of small arms, leading them to be used widely as marksman rifles.  The rifle won't cycle a round without the shooter doing it manually, causing less movement of parts and gases while the round is being fired.  This improves accuracy, but also increases recoil compared to automatic rifles of the same caliber.