Abstract: An ammunition comprises a cartridge casing and a propellant unit disposed in the cartridge casing including a propellant housing having a length oriented codirectionally with the length of the cartridge casing, a rear terminal portion held in a rear base of the casing and a frontal terminal portion provided with an external thread. The ammunition further has a projectile housing having a rear length portion received in the frontal end portion of the cartridge casing; and an annular sleeve affixed to the exterior face of the projectile housing base and being in alignment with the propellant housing. The annular sleeve has an internal thread being in a threaded engagement with the external thread of the propellant housing and weakened portions immediately adjacent the exterior face for causing a rupture of the annular sleeve in response to a predetermined propelling force seeking to separate the projectile housing from the cartridge casing upon igniting the propellant.