With the exception of the L98A1, the SA80 system is a selective fire gas-operated design that uses ignited powder gases bled through a port in the barrel to provide the weapon's automation. The rifle uses a short-stroke gas piston system located above the barrel, which is fed gas through a three-position adjustable gas regulator. The first gas setting is used for normal operation, the second is for use in difficult environmental conditions, while the third setting prevents any gas from reaching the piston and is used to launch rifle grenades. The weapon uses a rotating cylindrical bolt that contains 7 radially mounted locking splines, an extractor and casing ejector. The bolt's rotation is controlled by a cam pin that slides inside a helical camming guide machined into the bolt carrier.