Blowback (firearms)

Blowback is a system of operation for <a href="/facts/Semi-automatic_firearm/2mTJkWwp">self-loading</a> <a href="/facts/Firearm/GuHx4aGE">firearms</a> that obtains energy from the motion of the <a href="/facts/Cartridge_case/vjkWaDjM">cartridge case</a> as it is pushed to the rear by expanding gas created by the ignition of the <a href="/facts/Propellant_charge/K88ymXRy">propellant charge</a>.
Several blowback systems exist within this broad principle of operation, each distinguished by the methods used to control <a href="/facts/Bolt_(firearms)/mEpdypQk">bolt</a> movement. In most actions that use blowback operation, the <a href="/facts/Breech-loading_weapon/bCzCKg7n">breech</a> 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, delay opening of the breech until the bullet has left the barrel. A few locked breech designs use a form of blowback (example: primer actuation) to perform the unlocking function.
The blowback principle may be considered a simplified form of <a href="/facts/Gas-operated_reloading/CnKcFREy">gas operation</a>, since the cartridge case behaves like a piston driven by the powder gases. Other operating principles for self-loading firearms include <a href="/facts/Delayed_blowback/W0nlETr7">delayed blowback</a>, <a href="/facts/Blow_forward/QYRQd7ds">blow forward</a>, <a href="/facts/Gas-operated_reloading/CnKcFREy">gas operation</a>, and <a href="/facts/Recoil_operation/YpobDqQw">recoil operation</a>.

Blowback (firearms) open-in-new

Blowback (firearms)