What is Blowback?
{{no sources|date=July 2016}} '''Blowback''' is a system of operation for [[self-loading]] [[firearms]] that obtains [[energy]] from the motion of the [[Cartridge (firearms)|cartridge case]] as it is pushed to the rear by [[Thermal expansion|expanding gases]] created by the [[ignition]] of the [[propellant]] charge. Several blowback systems exist, distinguished by the methods used to control [[bolt]] movement. In most actions that use blowback operation, the [[breech]] is not locked mechanically at the time of firing: the inertia of the bolt and recoil spring(s), relative to the weight of the bullet, delays opening of the breech until the bullet has left the [[Barrel (weapons)|barrel.]] A few locked breech designs use a form of blowback (example: primer actuation) to perform the unlocking function. Other operating principles for self-loading firearms include blow forward, gas operation, [[Recoil|recoil operation]], [[revolver]], [[Gatling gun|Gatling]], and chain. The blowback principle may be considered a simplified form of gas operation, since the cartridge case behaves like a [[piston]] driven by the powder gases. ==Simple Blowback== Simple blowback operation is where the recoil of the cartridge moves the bolt rearwards to load the next round. This operation is found in [[Automatic firearm|automatic pistols]] and [[Submachine gun|submachine guns]] and firearms chambered in lower pressure rounds. The [[rifle]] rounds which have higher pressures are usually deemed unsuitable for simple blowback operation. However, there is Delayed Blowback where the chamber is locked until the pressures drop to a safe level to reload. ==Delayed Blowback== Delayed blowback is similar to simple blowback but is capable of handling the pressures of rifle rounds. It uses an operation that delays the opening of the bolt when firing. ===Lever delayed blowback=== Lever delayed blowback is where the bolt has a [[lever]] that slows the opening of the bolt but [[Acceleration|accelerates]] the bolt carrier, the bolt then also accelera