How Astra 400 work

Just a plain boring straight blowback operated, originally it was chambered for underpowered 9x23 Largo ballistically identical to 9x19mm both in term of pressure and power. What make this pistol unique and great for this era is that people can put almost every kind of 9mm caliber in this pistol and it still working fine because of the chamber and magazine that designed for longer case of 9x23 couple with heavy and strong coil spring