Schematic of an Extended Chamber Blowback operation (The example shown uses the barrels rifling as a helically fluted chamber for extra delay/ease of extraction)
Extended chamber blowback (ECB) is a closed bolt firing equivalent of Advanced Primer Ignition that uses straight-sided rebated rim cartridges in an extended deeper chambering to contain the gas pressure slightly longer until it reaches a safe level to extract. This operation is almost similar to a simple blowback operation, API blowback firearms that have fired the round at the point where the cartridge is fully chambered operate in a similar way.
