The invention discloses a bottom air bleeding type caseless ammunition. The bottom air bleeding type caseless ammunition comprises a bullet jacket, a core, a
piston barrel, a connecting rod and a
tail which are arranged in sequence from top to bottom, wherein a spring is sheathed on the outer side of the
piston barrel, a cylindrical body is arranged on the outer side of the connecting rod, a circle of baffle is arranged along the inner wall of the body, the upper end of the body is connected with the lower end of the bullet jacket and one end of the core is arranged in the
piston barrel; one end of the spring is arranged on the lower side of the upper edge of the piston barrel, the other end of the spring is arranged on the upper side of the baffle, a primer filling chamber is arranged at the bottom of the
tail and a vent is formed in the outer side of the
tail; the body, the connecting rod and the tail form a
propellant filling chamber, a primer is filled in the primer filling chamber and
gunpowder is filled in the
propellant filling chamber. The bottom air bleeding type caseless ammunition disclosed by the invention has the advantages that no case is remained when the caseless ammunition is shot, the corresponding firearm structure is simplified and the firearm weight is reduced; the problems that the traditional caseless ammunition is apt to self-ignite, the dud rate is high and the traditional caseless ammunition is apt to be affected with damp are solved, and the application scope is wide; and the
impact effect of the tail increases bullet
lethality.