What is Gas operation (firearms)?
'''Gas-operation''' is a system of operation used to provide energy to operate [[Semi-automatic firearm|autoloading]] [[Gun|firearms]]. In gas operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and insert a new cartridge into the chamber. Energy from the gas is harnessed through either a port in the barrel or a trap at the muzzle. This high-pressure gas impinges on a surface such as a [[piston]] head to provide motion for unlocking of the action, extraction of the spent case, ejection, cocking of the hammer or striker, [[wiktionary:chamber|chambering]] of a fresh cartridge, and locking of the action. == Long stroke == [[File:Gas OPR.gif|thumb|250px]] The [[AK-47]] is the most-produced rifle using long stroke gas operation. == Short stroke == [[File:PISTONM16.gif|thumb|250px]] Used in the AR-18. == Direct impingement == [[File:DIRECTM16.gif|thumb|250px]] Direct impingement is a form of gas operation that does away with the piston completely. The bolt is designed in such a way so that the gas acts directly upon the bolt (hence the name) to cycle the action. Used in the AR-15. == Fluted chamber direct impingement == [[File:Gasrücklader Kinematik CC BY-SA 4.0 Autor RRT877.svg|thumb|250px]] Another form of direct impingement using a fluted chamber instead of a gas port. With this operation, the gas circumvents around the chambered cartridge through the grooves of the fluted chamber surpassing through the locking lugs to the front of the bolt carrier that operates as a gas piston unlocking the bolt to cycle the weapons operation. == Floating chamber == Early machine guns were expensive to operate. The [[United States Army]] wanted to train [[machine gun]] crews with less-expensive ammunition. To do this, they needed the .22 LR cartridge to operate firearms designed to use the .30-06 cartridge. David Marshall Williams invented a method that involved a separate floating chamber that acted as a gas piston with combustion gas impinging direct